EXECUTION COPY
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              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.,
                                   Depositor,
                           WASHINGTON MUTUAL BANK, FA
                              Seller and Servicer,
                         BANK ONE, NATIONAL ASSOCIATION
                                    Trustee,
                                ----------------
              AMENDED AND RESTATED POOLING AND SERVICING AGREEMENT
                          Dated as of November 1, 2001
                                   relating to
             WASHINGTON MUTUAL BANK, FA MORTGAGE-BACKED PASS-THROUGH
          CERTIFICATES, SERIES 1999-WM4 AND WASHINGTON MUTUAL BANK, FA
           MORTGAGE-BACKED PASS-THROUGH CERTIFICATES, SERIES 2001-AR5
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                                TABLE OF CONTENTS
                                                                            PAGE
ARTICLE I    DEFINITIONS.......................................................4
ARTICLE II   CONVEYANCE OF TRUST FUND; REPRESENTATIONS AND WARRANTIES.........35
     SECTION 2.01    Conveyance of Trust Fund.................................35
     SECTION 2.02    Acceptance by Trustee....................................37
     SECTION 2.03    Representations, Warranties and Covenants of the
                     Servicer and Seller......................................38
     SECTION 2.04    Representations, Warranties and Covenants of the Seller
                     with respect to the Mortgage Loans.......................40
     SECTION 2.05    Issuance of Certificates.................................47
     SECTION 2.06    REMIC Provisions.........................................47
ARTICLE III  ADMINISTRATION AND SERVICING OF MORTGAGE LOANS...................52
     SECTION 3.01    Servicing Standard.......................................52
     SECTION 3.02    Enforcement of the Obligations of Sub-Servicers..........53
     SECTION 3.03    Termination of the Rights of Sub-Servicers...............53
     SECTION 3.04    Liability of the Servicer................................54
     SECTION 3.05    Rights of the Depositor and the Trustee in Respect of
                     the Servicer.............................................54
     SECTION 3.06    Trustee to Act as Servicer...............................54
     SECTION 3.07    Collection of Mortgage Loan Payments.....................55
     SECTION 3.08    Collection of Taxes, Assessments and Similar Items;
                     Escrow Accounts..........................................57
     SECTION 3.09    Permitted Withdrawals from the Custodial Account.........57
     SECTION 3.10    Maintenance of Primary Mortgage Insurance Policies;
                     Collections Thereunder...................................59
     SECTION 3.11    Maintenance of Hazard Insurance and Other Insurance......60
     SECTION 3.12    Enforcement of Due-On-Sale Clauses; Assumption
                     Agreements...............................................61
     SECTION 3.13    Realization Upon Defaulted Mortgage Loans................62
     SECTION 3.14    Trustee to Cooperate; Release of Trustee Mortgage Files..64
     SECTION 3.15    Documents, Records and Funds in Possession of Servicer
                     to be Held for the Trustee for the Benefit of the
                     Certificateholders.......................................65
     SECTION 3.16    Servicing Compensation; Compensating Interest............65
     SECTION 3.17    Reports to the Depositor; Account Statements.............66
     SECTION 3.18    Annual Statement as to Compliance........................66
     SECTION 3.19    Annual Independent Public Accountants' Servicing Report..67
     SECTION 3.20    Reports to Trustee.......................................67
                                      -i-
                                TABLE OF CONTENTS
                                   (CONTINUED)
                                                                            PAGE
ARTICLE IV   PAYMENTS AND STATEMENTS TO CERTIFICATEHOLDERS....................67
     SECTION 4.01    Certificate Account......................................67
     SECTION 4.02    Distributions............................................68
     SECTION 4.03    Allocation of Realized Losses............................70
     SECTION 4.04    Monthly Statements to Certificateholders.................71
     SECTION 4.05    Prepayment Interest Shortfalls and Relief Act
                     Shortfalls...............................................73
ARTICLE V    ADVANCES.........................................................74
     SECTION 5.01    Monthly Advances by the Servicer.........................74
     SECTION 5.02    Advances for Attorneys' Fees.............................74
     SECTION 5.03    Nonrecoverable Advances..................................75
     SECTION 5.04    Advance Procedures.......................................75
ARTICLE VI   THE CERTIFICATES.................................................75
     SECTION 6.01    The Certificates.........................................75
     SECTION 6.02    Registration of Transfer and Exchange of Certificates....77
     SECTION 6.03    Mutilated, Destroyed, Lost or Stolen Certificates........83
     SECTION 6.04    Persons Deemed Owners....................................83
     SECTION 6.05    Access to List of Certificateholders' Names and
                     Addresses................................................83
     SECTION 6.06    Maintenance of Office or Agency..........................84
ARTICLE VII  THE DEPOSITOR, SELLER AND THE SERVICER...........................84
     SECTION 7.01    Liabilities of the Depositor, Seller and the Servicer....84
     SECTION 7.02    Merger or Consolidation of the Depositor, the Seller
                     or the Servicer..........................................85
     SECTION 7.03    Limitation on Liability of the Depositor, the Servicer
                     and Others...............................................86
     SECTION 7.04    Servicer Not to Resign...................................86
     SECTION 7.05    Errors and Omissions Insurance; Fidelity Bonds...........86
     SECTION 7.06    Seller and Servicer May Own Certificates.................87
ARTICLE VIII DEFAULT..........................................................87
     SECTION 8.01    Events of Default........................................87
     SECTION 8.02    Trustee to Act; Appointment of Successor.................88
     SECTION 8.03    Notification to Certificateholders.......................89
     SECTION 8.04    Waiver of Events of Default..............................90
                                      -ii-
                                TABLE OF CONTENTS
                                   (CONTINUED)
                                                                            PAGE
ARTICLE IX   CONCERNING THE TRUSTEE...........................................90
     SECTION 9.01    Duties of Trustee........................................90
     SECTION 9.02    Certain Matters Affecting the Trustee....................92
     SECTION 9.03    Trustee Not Liable for Certificates or Mortgage Loans....93
     SECTION 9.04    Trustee May Own Certificates.............................93
     SECTION 9.05    Trustee's Compensation and Expenses......................93
     SECTION 9.06    Eligibility Requirements for Trustee.....................94
     SECTION 9.07    Resignation and Removal of Trustee.......................94
     SECTION 9.08    Successor Trustee........................................95
     SECTION 9.09    Merger or Consolidation of Trustee.......................95
     SECTION 9.10    Appointment of Co-Trustee or Separate Trustee............95
     SECTION 9.11    Office of the Trustee....................................97
     SECTION 9.12    Tax Returns..............................................97
ARTICLE X    TERMINATION......................................................97
     SECTION 10.01   Termination upon Liquidation or Repurchase of all
                     Mortgage Loans...........................................97
     SECTION 10.02   Procedure Upon Optional or Other Final Termination.......98
     SECTION 10.03   Additional Termination Requirements......................99
ARTICLE XI   MISCELLANEOUS PROVISIONS........................................100
     SECTION 11.01   Amendment...............................................100
     SECTION 11.02   Recordation of Agreement; Counterparts..................101
     SECTION 11.03   Governing Law...........................................101
     SECTION 11.04   Intention of Parties....................................101
     SECTION 11.05   Notices.................................................103
     SECTION 11.06   Severability of Provisions..............................103
     SECTION 11.07   Limitation on Rights of Certificateholders..............103
     SECTION 11.08   Certificates Nonassessable and Fully Paid...............104
EXHIBIT A   FORM OF CLASS A CERTIFICATE......................................A-1
EXHIBIT A-1 FORM OF CLASS I-A CERTIFICATE .................................A-1-1
EXHIBIT A-2 FORM OF CLASS B-1, B-2 AND B-3 CERTIFICATE ....................A-2-1
EXHIBIT A-3 FORM OF CLASS B-4, B-5 AND B-6 CERTIFICATE ....................A-3-1
EXHIBIT B   FORM OF CLASS R CERTIFICATE......................................B-1
                                      -iii-
                                TABLE OF CONTENTS
                                   (CONTINUED)
                                                                            PAGE
EXHIBIT B-1 FORM OF CLASS I-R CERTIFICATE..................................B-1-1
EXHIBIT C   SCHEDULE OF MORTGAGE LOANS.......................................C-1
EXHIBIT D-1 FORM OF INITIAL CERTIFICATION OF TRUSTEE.......................D-1-1
EXHIBIT D-2 FORM OF CERTIFICATION OF TRUSTEE...............................D-2-1
EXHIBIT E   FORM OF REQUEST FOR RELEASE......................................E-1
EXHIBIT F   FORM OF INVESTOR REPRESENTATION LETTER...........................F-1
EXHIBIT G   FORM OF TRANSFEROR REPRESENTATION LETTER.........................G-1
EXHIBIT H   FORM OF INVESTOR TRANSFER AFFIDAVIT AND AGREEMENT................H-1
EXHIBIT I   FORM OF TRANSFER CERTIFICATE.....................................I-1
EXHIBIT J   FORM OF ALLONGE..................................................J-1
EXHBIT K    REQUEST FOR EXCHANGE.............................................K-1
                                      -iv-
          THIS AMENDED AND RESTATED POOLING AND SERVICING AGREEMENT, dated as of
November  1, 2001 (the  "Agreement"),  is hereby  executed  by and among  CREDIT
SUISSE FIRST BOSTON  MORTGAGE  SECURITIES  CORP.,  depositor (the  "Depositor"),
WASHINGTON MUTUAL BANK, FA ("Washington Mutual"), in its capacity as seller (the
"Seller")  and in its  capacity  as  servicer  (the  "Servicer")  and BANK  ONE,
NATIONAL   ASSOCIATION,   a  national  banking  association,   as  trustee  (the
"Trustee").
          WHEREAS,  the Depositor,  Washington  Mutual,  and the Trustee entered
into that certain  Pooling and Servicing  Agreement dated as of December 1, 1999
(the  "Original  Pooling and Servicing  Agreement"),  as amended by that certain
First Amendment To Pooling and Servicing  Agreement,  dated as of July 31, 2000,
by and among the  Depositor,  Washington  Mutual  and the  Trustee  (the  "First
Amendment" and, together with the Original Pooling and Servicing Agreement,  the
"Amended Pooling Agreement").
          WHEREAS,  the Depositor,  Washington  Mutual,  and the Trustee wish to
amend and restate the Amended  Pooling  Agreement as of November 1, 2001, on the
terms and conditions set forth in this Agreement; except as otherwise amended as
of November 1, 2001 and by the First Amendment, the terms and conditions of this
Agreement shall be as set forth in the Original Pooling and Servicing Agreement.
          Capitalized  terms used in this  Agreement and not  otherwise  defined
will have the meanings assigned to them in Article I below.
                              PRELIMINARY STATEMENT
          The  Depositor  is the  owner  of the  Mortgage  Loans  and the  other
property  being  conveyed by it to the Trustee in its capacity as trustee of the
Trust Fund,  in  accordance  with this  Agreement,  and the  Depositor  has duly
authorized  the  execution  and  delivery of this  Agreement  to provide for the
conveyance to the Trustee of the Trust Fund.
          As  provided  herein,  the  Depositor  will  elect to treat the assets
consisting of the Mortgage Loans and certain other assets as described herein as
a real estate  mortgage  investment  conduit (a "remic") for federal  income tax
purposes,  and such  segregated  pool of assets will be designated as the "Trust
REMIC." The Class R  Certificates  will  represent  the sole class of  "residual
interests" in the Trust REMIC for purposes of the REMIC  Provisions  (as defined
herein) under federal income tax law. The following table irrevocably sets forth
the designation,  Certificate  Rate,  aggregate  Initial  Certificate  Principal
Balance  and  Maturity  Date  for  each  Class of  Certificates  comprising  the
interests  representing  "regular  interests"  in the Trust  REMIC  (the  "REMIC
Regular  Certificates").  The "latest possible maturity date" (determined solely
for purposes of satisfying Treasury Regulation Section  1.860G-1(a)(4)(iii)) for
each Class of REMIC Regular  Certificates  shall be the first  Distribution Date
that  follows the stated  maturity  date for the Mortgage  Loan  included in the
Trust Fund as of the  Closing  Date with the  longest  remaining  term to stated
maturity.
                                      -1-
                   CERTIFICATE PRINCIPAL                           INITIAL
    DESIGNATION           BALANCES           MATURITY DATE     PASS-THROUGH RATE
    -----------           --------           -------------     -----------------
     Class A-1         $202,311,568.63      August 19, 2039         6.3722%
     Class A-2         $664,303,305.20     December 19, 2039        6.4386%
     Class A-3         $391,241,788.84      August 19, 2039         6.2696%
     Class A-4         $846,039,005.17     November 19, 2039        6.8277%
     Class A-5         $131,913,632.22     February 19, 2039        6.1608%
     Class A-6         $185,410,324.26     January 19, 2039         6.7428%
     Class A-7         $104,808,047.56     November 19, 2039        6.2580%
     Class A-8         $479,291,431.90     November 19, 2039        6.9929%
     Class A-9         $535,029,262.10     November 19, 2029        6.7386%
      Class R              $100.00         November 19, 2039        6.7386%
          All covenants and agreements made by the Depositor  herein are for the
benefit and security of the  Certificateholders.  The Depositor is entering into
this  Agreement,  and the Trustee is  accepting  the trusts  created  hereby and
thereby,  for good and valuable  consideration,  the receipt and  sufficiency of
which are hereby  acknowledged.  The aggregate Principal Balance of the Mortgage
Loans as of the Cut-off Date is $3,540,348,465.88.
          The Depositor is the owner of the of the Class A-1,  Class A-2,  Class
A-3 and Class A-4  Certificates  and the other  property being conveyed by it to
the Trustee in its  capacity as trustee of the Trust Fund,  in  accordance  with
this Agreement.
          As  provided  herein,  the  Depositor  will  elect to treat the assets
consisting of the Class A-1, Class A-2 Class A-3 and Class A-4  Certificates and
certain other assets as described  herein as a real estate  mortgage  investment
conduit (a "remic") for federal income tax purposes, and such segregated pool of
assets will be designated as "REMIC I." The Class R-I Component evidenced by the
Class I-R Certificates will represent the sole class of "residual  interests" in
REMIC I for purposes of the REMIC  Provisions (as defined  herein) under federal
income  tax  law.  The  "regular  interests"  in REMIC I ("the  REMIC I  Regular
Interests")  will be  uncertificated  interests on  corresponding to each of the
Mortgage  Loans  identified on the Mortgage Loan Schedule X ("Class AR5 Mortgage
Loans") or Mortgage Loan Schedule Y ("Class Y Mortgage Loans"). Ownership of the
uncertificated regular interests corresponding to Class Y Mortgage Loans will be
represented  by  the  Class  Y  Certificates.  The  REMIC  I  Regular  Interests
corresponding to Mortgage Loans in Mortgage Loan Schedule X shall be referred to
as the "Class AR5  Regular  Interests."  The  "latest  possible  maturity  date"
(determined  solely for  purposes  of  satisfying  Treasury  Regulation  Section
1.860G-1(a)(4)(iii))  for each Class of REMIC Regular  Certificates shall be the
first  Distribution  Date that follows the stated maturity date for the Mortgage
Loan  included  in the  Trust  Fund as of the  Closing  Date  with  the  longest
remaining  term to stated  maturity.  Each REMIC I Regular  Interest will have a
principal  balance equal to the Principal  Balance of the Mortgage Loan to which
it  corresponds  and will bear interest at a rate equal to the Net Mortgage Rate
on such Mortgage Loan. Principal and interest  distributed,  and Realized Losses
allocated, to REMIC II Certificates that were incurred with respect to Class AR5
and Class Y Mortgage  Loans shall be deemed to have been  distributed in respect
of and allocated to the REMIC I Regular Interest  corresponding to such Mortgage
Loan.
                                      -2-
          As  provided  herein,  the  Depositor  will  elect to treat the assets
consisting of the uncertificated interests in REMIC I representing the Class AR5
Regular  Interests and certain other assets as described herein as a real estate
mortgage  investment  conduit (a "remic") for federal  income tax purposes,  and
such  segregated  pool of assets will be designated as the "REMIC II." The Class
R-II Component  evidenced by the Class I-R Certificates  will represent the sole
class of "residual  interests" in REMIC II for purposes of the REMIC  Provisions
(as  defined   herein)  under  federal  income  tax  law.  The  following  table
irrevocably sets forth the designation,  aggregate Initial Certificate Principal
Balance  and  Maturity  Date  for  each  Class of  Certificates  comprising  the
interests  representing  "regular  interests"  in REMIC II  ("REMIC  II  Regular
Certificates").  The "latest  possible  maturity  date"  (determined  solely for
purposes of satisfying Treasury Regulation Section 1.860G-1(a)(4)(iii)) for each
Class of REMIC Regular  Certificates  shall be the first  Distribution Date that
follows the stated  maturity  date for the Mortgage  Loan  included in the Trust
Fund as of the Class AR5 Delivery Date with the longest remaining term to stated
maturity.
                       AGGREGATE INITIAL
                    CERTIFICATE PRINCIPAL                             RATING
    DESIGNATION            BALANCES           MATURITY DATE         ▇▇▇▇▇'▇/S&P
    -----------            --------           -------------         -----------
     Class I-A           $ 808,071,900      December 19, 2039         Aaa/AAA
     Class B-1           $ 10,440,000       December 19, 2039         Aa2/AA
     Class B-2            $ 7,517,000       December 19, 2039          A2/A
     Class B-3            $ 3,758,000       December 19, 2039        Baa2/BBB
     Class B-4            $ 1,670,000       December 19, 2039         Ba2/BB
     Class B-5            $ 1,253,000       December 19, 2039          Ba2/B
     Class B-6          $ 2,506,666.11      December 19, 2039           N/A
     Class I-R            $100.00(1)        December 19, 2029         N/A/AAA
(1) The  entire  principal  balance  of the  Class  I-R  Certificates  shall  be
represented by the Class R-II Component.
          The parties hereto intend to effect an absolute sale and assignment of
the Mortgage  Loans to the Trustee for the benefit of  Certificateholders  under
the Mortgage Loan Purchase Agreement and this Agreement. However, the Seller and
the Depositor will hereunder  absolutely assign,  and as a precautionary  matter
grant a security  interest in and to, its rights,  if any, in the Trust Fund and
the Mortgage Loans to the Trustee on behalf of Certificateholders to ensure that
the interest of the Certificateholders  hereunder in the Mortgage Loans is fully
protected.
                                WITNESSETH THAT:
          In  consideration  of the  mutual  agreements  herein  contained,  the
Depositor, the Servicer, the Seller and the Trustee agree as follows:
                                      -3-
                                    ARTICLE I
                                   DEFINITIONS
          Whenever  used in this  Agreement,  the  following  words and phrases,
unless the context otherwise requires, shall have the following meanings:
          ADDITIONAL SERVICING FEE: For each calendar month for so long as REMIC
I remains in existence  and with respect to each Class AR5 Regular  Interest and
the related Class AR5 Mortgage Loan, an amount equal to one month's interest (or
in the event of any payment of interest which accompanies a Principal Prepayment
in Full, interest for the number of days covered by such payment of interest) at
a rate equal to the  Additional  Servicing  Fee Rate on such  Class AR5  Regular
Interest and the related Class AR5 Mortgage Loan.
          ADDITIONAL SERVICING FEE RATE: With respect to each Class AR5 Mortgage
Loan, a per annum rate equal to 0.825%.
          ADJUSTMENT  DATE:  As to each Mortgage Loan that does not bear a fixed
Mortgage  Rate,  each date set forth in the  related  Mortgage  Note on which an
adjustment to the interest rate on such Mortgage Loan becomes effective.
          ADVERSE REMIC EVENT: As defined in Section 2.06(f).
          AGREEMENT:  This Amended and Restated Pooling and Servicing  Agreement
and any and all exhibits, amendments or supplements hereto.
          APPRAISED VALUE:  The appraised value of the Mortgaged  Property based
upon the appraisal made for the originator at the time of the origination of the
related  Mortgage Loan or the sales price of the Mortgaged  Property at the time
of such  origination,  whichever is less,  or with respect to any Mortgage  Loan
that  represents a refinancing,  the lower of the appraised value at origination
or the appraised  value of the Mortgaged  Property based upon the appraisal made
at the time of such refinancing.
          ASSIGNMENT:  An assignment from the Seller, in blank, of the Mortgage,
in recordable form,  sufficient  under the laws of the jurisdiction  wherein the
related  Mortgaged  Property is located to reflect,  if recorded,  of record the
absolute sale and assignment of the Mortgage Loan to the Trustee for the benefit
of  Certificateholders,  which  assignment,  may be in the  form  of one or more
blanket assignments  covering Mortgages secured by Mortgaged  Properties located
in the same county, if permitted by law and accompanied by an Opinion of Counsel
to that effect.
          AVAILABLE  DISTRIBUTION  AMOUNT: With respect to any Distribution Date
and each of Loan  Group 5, Loan  Group 6, Loan Group 7, Loan Group 8, Loan Group
9, the Class AR5  Mortgage  Loans as a group and the Class Y Mortgage  Loan as a
group, the excess of:
          (1) the sum of (i) the  aggregate  amount of payments and  collections
received by the  Servicer in respect of each  Mortgage  Loan in such Loan Group,
the Class AR5  Mortgage  Loans or the Class Y Mortgage  Loans on or prior to the
related  Determination  Date  and not  previously  remitted,  from  any  source,
including  amounts  received  from the related  Mortgagor,  Insurance  Proceeds,
Liquidation  Proceeds (net of related  Liquidation  Expenses)  and  condemnation
awards,
                                      -4-
and amounts  received in connection  with the purchase of any Mortgage  Loans by
the Seller or Servicer and the  substitution of Replacement  Mortgage Loans, and
excluding  interest  and other  earnings on amounts on deposit in or credited to
the Custodial Account and the Certificate Account, and (ii) the aggregate amount
of Monthly Advances and Compensating  Interest allocated to such Loan Group, the
Class AR5 Mortgage  Loans or the Class Y Mortgage  Loans required to be remitted
by the Servicer relating to such Distribution Date;
minus
          (2) the sum of (i) the aggregate amount of the servicing  compensation
to be paid to the  Servicer  pursuant to the terms  hereof  (including,  without
limitation,  Servicing  Fees, and, with respect to the Class AR5 Mortgage Loans,
the  Additional  Servicing Fee,  prepayment  penalties,  fees or premiums,  late
payment charges and assumption  fees and any excess interest  charges payable by
the Mortgagor by virtue of any default or other  non-compliance by the Mortgagor
with the terms of the Mortgage Loan or any other instrument or document executed
in  connection  therewith  or  otherwise),  (ii)  any  amount  included  therein
representing  late  payments  or  other  recoveries  of  principal  or  interest
(including  Liquidation  Proceeds  (net  of  Liquidation  Expenses),   Insurance
Proceeds and condemnation  awards) with respect to any Mortgage Loans in respect
of which the Servicer has made a previously  unreimbursed Monthly Advance to the
extent of such Monthly  Advance,  (iii) amounts  included  therein  representing
reimbursement  of  Nonrecoverable  Advances  and other  amounts  permitted to be
withdrawn  from the  Custodial  Account  or the  Certificate  Account,  (iv) all
Monthly Payments or portions thereof (other than Principal Prepayments and other
unscheduled collections of principal) received in respect of scheduled principal
and interest on any Mortgage  Loan due after the related Due Period and included
therein,  (v) all payments  due on any Mortgage  Loan on or prior to the Cut-off
Date and included therein, and (vi) Principal  Prepayments and other unscheduled
collections  of  principal  received  after the  related  Prepayment  Period and
included  therein,  in all cases,  allocated  to such Loan Group,  the Class AR5
Mortgage Loans, and the Class Y Certificates.
          The Available  Distribution Amount, when used without reference to any
such Loan Group,  the Class AR5  Mortgage  Loans or the Class Y Mortgage  Loans,
means the sum of the  Available  Distribution  Amounts for all such Loan Groups,
the Class AR5 Mortgage Loans and the Class Y Mortgage Loans.
          BANKRUPTCY  COVERAGE:  $100,000 less (a) any scheduled or  permissible
reduction in the amount of Bankruptcy  Coverage  pursuant to this definition and
(b) Bankruptcy Losses allocated to the Class AR Certificates.
          The Bankruptcy Coverage may be reduced upon written  confirmation from
the Rating  Agencies  that such  reduction  will not  adversely  affect the then
current ratings assigned to the Class AR5 Certificates by the Rating Agencies.
          BANKRUPTCY  LOSS: A loss on a Class AR5  Mortgage  Loan arising out of
(i) a reduction in the  scheduled  Monthly  Payment for such  Mortgage Loan by a
court of competent  jurisdiction in a case under the Bankruptcy Code, other than
any  such  reduction  that  arises  out of  clause  (ii) of this  definition  of
"Bankruptcy  Loss,"  including,  without  limitation,  any such  reduction  that
results in a permanent  forgiveness  of  principal,  or (ii) with respect to any
Class AR5 Mortgage Loan, a valuation,  by a court of competent jurisdiction in a
case under such Bankruptcy Code, of the related
                                      -5-
Mortgaged Property in an amount less than the then outstanding Principal Balance
of such Mortgage Loan.
          BANKRUPTCY  CODE: The United States  Bankruptcy  Code, as amended from
time to time (11 U.S.C.).
          BOOK-ENTRY  CERTIFICATES:  The Class I-A  Certificates and the Class B
Certificates.
          BUSINESS DAY: Any day other than (i) a Saturday or a Sunday, or (ii) a
day on which banking institutions in New York or the state in which the Servicer
or the Corporate  Trust Office are located are authorized or obligated by law or
executive order to be closed.
          CASH  LIQUIDATION:  As to any  defaulted  Mortgage  Loan  other than a
Mortgage Loan as to which an REO Acquisition  occurred,  a determination  by the
Servicer that it has received all Insurance Proceeds,  Liquidation  Proceeds and
other  payments or cash  recoveries  which the Servicer  reasonably  and in good
faith expects to be finally recoverable with respect to such Mortgage Loan.
          CERTIFICATE:  Any Class A-1,  Class A-2,  Class A-3,  Class A-4, Class
A-5,  Class A-6,  Class A-7,  Class A-8,  Class A-9, Class I-A, Class B-1, Class
B-2, Class B-3, Class B-4, Class B-5 Class B-6, Class R or Class I-R Certificate
executed   and   authenticated   by  the   Trustee   for  the   benefit  of  the
Certificateholders  in  substantially  the form or forms  attached  as  Exhibits
hereto.
          CERTIFICATE  ACCOUNT:  The  separate  account or accounts  created and
maintained  by the Trustee  pursuant to Section 4.01, in the name of the Trustee
for  the  benefit  of  the   Certificateholders  for  deposit  of  payments  and
collections  in respect of the Mortgage  Loans  pursuant to Section 4.01 hereof,
which account or accounts must be an Eligible Account or Accounts.
          CERTIFICATE  OWNER:  With  respect to a  Book-Entry  Certificate,  the
Person who is the beneficial owner of such Book-Entry Certificate.
          CERTIFICATE  PRINCIPAL  BALANCE:  On any date and with respect to each
Certificate,  the Initial  Certificate  Principal Balance of such Certificate as
specified  on the  face  thereof  less  the  sum of (i) all  amounts  previously
distributed to the Holder of such  Certificate (or any predecessor  Certificate)
with  respect to  principal  pursuant  to Section  4.02 and (ii) all  amounts of
Realized  Losses  previously  allocated to such  Certificate (or any predecessor
Certificate)  pursuant to Section 4.03;  provided however,  that the Certificate
Principal  Balance  for any class of Class A  Certificates  shall not exceed the
aggregate Principal Balance of the related Loan Group and provided further, that
the aggregate  Certificate Principal Balance of the Class AR5 Certificates shall
not exceed the aggregate Principal Balance of the Class AR5 Mortgage Loans.
          CERTIFICATE   RATE:  In  the  case  of  each  Class  of  the  Class  A
Certificates  and Class R Certificates  and any  Distribution  Date, a per annum
rate  equal to the  weighted  average,  expressed  as a  percentage,  of the Net
Mortgage Rates of the Mortgage Loans in the related Loan Group,  weighted on the
basis of the respective  Principal  Balances of such Mortgage Loans  immediately
preceding such Distribution Date.  Interest on the Certificates will be computed
on the basis of a 360-day year comprised of twelve 30-day months.
          CERTIFICATE  REGISTER:  The  register  maintained  pursuant to Section
6.02(a) hereof.
                                      -6-
          CERTIFICATEHOLDER or HOLDER: The Person in whose name a Certificate is
registered in the Certificate Register.
          CLASS: Collectively, each class of Class A Certificates, each class of
Class  I-A  Certificates,  each  class  of  Class B  certificates,  the  Class R
Certificates and the Class I-R Certificates..
          CLASS A CERTIFICATES:  The Class A-1, Class A-2, Class A-3, Class A-4,
the Class A-5, Class A-6, Class A-7, Class A-8 and Class A-9 Certificates.
          CLASS A CUMULATIVE INTEREST SHORTFALL AMOUNT: On any Distribution Date
and with  respect to any Class of Class A  Certificates,  an amount equal to (i)
any portion of the  related  Class A Interest  Distribution  Amount that was not
distributed  to the  Holders  of such  Class  A  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
A Certificates on or prior to such Distribution Date.
          CLASS A INTEREST  DISTRIBUTION  AMOUNT:  On any Distribution  Date and
with  respect  to any  Class of Class A  Certificates,  (a)  one-twelfth  of the
product  of (i) the  aggregate  Certificate  Principal  Balance  of the  Class A
Certificates as of the last day of the related  Interest Accrual Period and (ii)
the related  Certificate  Rate,  minus (b) the  aggregate  amount of  Prepayment
Interest   Shortfalls  and  Relief  Act   Shortfalls   relating  to  Loan  Group
representing   such  Class  A  Certificates   and  allocated  to  such  Class  A
Certificates pursuant to Section 4.05 on such Distribution Date.
          CLASS A PRINCIPAL DISTRIBUTION AMOUNT: As to any Distribution Date and
with respect to any Class of Class A Certificates, an amount equal to the lesser
of (i) the balance of the  Available  Distribution  Amount  relating to the Loan
Group  representing  such  Class of Class A  Certificates  remaining  after  the
distribution  of all  amounts  required  to be  distributed  pursuant to Section
4.02(a)(x)(ii)  and (ii) the  aggregate  Certificate  Principal  Balance of such
Class.
          CLASS A-1  CERTIFICATE:  A Certificate,  designated Class A-1 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-2  CERTIFICATE:  A Certificate,  designated Class A-2 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-3  CERTIFICATE:  A Certificate,  designated Class A-3 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-4  CERTIFICATE:  A Certificate,  designated Class A-4 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
                                      -7-
          CLASS A-5  CERTIFICATE:  A Certificate,  designated Class A-5 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-6  CERTIFICATE:  A Certificate,  designated Class A-6 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-7 CERTIFICATE: A Certificate, designated as Class A-7 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-8 CERTIFICATE: A Certificate, designated as Class A-8 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS A-9 CERTIFICATE: A Certificate, designated as Class A-9 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A  hereto,  and  evidencing   ownership  of  interests  designated  as  "regular
interests" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS  AR5  CERTIFICATES:  The  Class  I-A,  Class  B  and  Class  I-R
Certificates.
          CLASS AR5 CUT-OFF DATE: November 1, 2001.
          CLASS AR5 DELIVERY DATE: December 6, 2001.
          CLASS AR5  DISTRIBUTION  AMOUNT:  The  Available  Distribution  Amount
allocable to the Class AR5 Mortgage Loans.
          CLASS AR5 MORTGAGE  LOANS:  Each of the  Mortgage  Loans listed on the
Mortgage Loan Schedule X.
          CLASS AR5 NET MORTGAGE RATE: As to each Class AR5 Regular Interest and
the related Class AR5 Mortgage Loan,  with respect to any  Distribution  Date, a
rate per annum  equal to (a) the  Mortgage  Rate in effect as of the Due Date in
the preceding calendar month minus (b) the sum of the Servicing Fee Rate and the
Additional Servicing Fee Rate.
          CLASS AR5 NET  WEIGHTED  AVERAGE  MORTGAGE  RATE:  With respect to any
Distribution  Date, the weighted  average of the Class AR5 Net Mortgage Rates as
of the first day of the relate Due Period.
          CLASS AR5 OPTIONAL TERMINATION:  The purchase of the assets of REMIC I
pursuant to Section 10.01(b).
                                      -8-
          CLASS AR5 OPTIONAL  TERMINATION  DATE:  The date fixed by the Servicer
for the purchase of the Class AR5 Mortgage Loans pursuant to Section 10.01(b).
          CLASS AR5  PASS-THROUGH  RATE: With respect to each Class of Class AR5
Certificates  and each  Distribution  Date,  the Class AR5 Net Weighted  Average
Mortgage Rate.
          CLASS AR5 REGULAR  INTEREST:  As defined in the Preliminary  Statement
hereto.
          CLASS I-A  CERTIFICATE:  A Certificate,  designated Class I-A executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-1  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS I-A CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class I-A  Certificate,  an amount equal to (i) any
portion of the  related  Class I-A  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class I-A  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
I-A Certificates on or prior to such Distribution Date.
          CLASS I-A INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class I-A  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class I-A Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to the  Class I-A
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
          CLASS B CERTIFICATES:  The Class B-1, Class B-2, Class B-3, Class B-4,
Class B-5 and Class B-6 Certificates.
          CLASS B PERCENTAGE:  With respect to any date of determination and any
Class of Class B Certificates,  the Certificate  Principal Balances of the Class
B-1, Class B-2, Class B-3,  Class B-4, Class B-5 or Class B-6  Certificates,  as
applicable,  divided by the aggregate of the Certificate  Principal  Balances of
the Class B Certificates.
          CLASS B-1  CERTIFICATE:  A Certificate,  designated Class B-1 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-2  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-1 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-1  Certificate,  an amount equal to (i) any
portion of the  related  Class B-1  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-1  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-1 Certificates on or prior to such Distribution Date.
                                      -9-
          CLASS B-1 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-1  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-1 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-1
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
          CLASS B-2  CERTIFICATE:  A Certificate,  designated Class B-2 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-2  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-2 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-2 Certificates,  an amount equal to (i) any
portion of the  related  Class B-2  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-2  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-2 Certificates on or prior to such Distribution Date.
          CLASS B-2 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-2  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-2 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-2
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
          CLASS B-3  CERTIFICATE:  A Certificate,  designated Class B-3 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-2  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-3 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-3  Certificate,  an amount equal to (i) any
portion of the  related  Class B-3  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-2  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-3 Certificates on or prior to such Distribution Date.
          CLASS B-3 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-3  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-3 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-3
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation of the interest portion of
                                      -10-
Special Hazard Losses in excess of the Special  Hazard  Coverage  Amount,  Fraud
Losses in excess of the Fraud  Coverage and  Bankruptcy  Losses in excess of the
Bankruptcy Coverage pursuant Section 4.03 on such Distribution Date.
          CLASS B-4  CERTIFICATE:  A Certificate,  designated Class B-4 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-2  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-4 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-4  Certificate,  an amount equal to (i) any
portion of the  related  Class B-4  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-4  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-4 Certificates on or prior to such Distribution Date.
          CLASS B-4 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-4  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-4 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-4
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
          CLASS B-5  CERTIFICATE:  A Certificate,  designated Class B-5 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-3  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-5 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-5  Certificate,  an amount equal to (i) any
portion of the  related  Class B-5  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-5  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-5 Certificates on or prior to such Distribution Date.
          CLASS B-5 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-5  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-5 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-5
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
                                      -11-
          CLASS B-6  CERTIFICATE:  A Certificate,  designated Class B-6 executed
and  authenticated by the Trustee in substantially the form set forth in EXHIBIT
A-3  hereto,  and  evidencing  ownership  of  interests  designated  as "regular
interests" in REMIC II for purposes of the REMIC Provisions.
          CLASS B-6 CUMULATIVE  INTEREST  SHORTFALL  AMOUNT: On any Distribution
Date and with respect to any Class B-6  Certificate,  an amount equal to (i) any
portion of the  related  Class B-6  Interest  Distribution  Amount  that was not
distributed  to the  Holders of such  Class B-6  Certificates  on any  preceding
Distribution  Date less (ii) any amount  described  in clause (i) hereof that is
included in a Realized Loss that has been allocated to the Holders of such Class
B-6 Certificates on or prior to such Distribution Date.
          CLASS B-6 INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class B-6  Certificates,  (a)  one-twelfth of the product of
(i) the aggregate Certificate Principal Balance of the Class B-6 Certificates as
of the last day of the  related  Interest  Accrual  Period and (ii) the  related
Class AR5  Pass-Through  Rate,  minus  (b) the  aggregate  amount of  Prepayment
Interest  Shortfalls  and  Relief  Act  Shortfalls  allocated  to such Class B-6
Certificates pursuant to Section 4.05 on such Distribution Date and the Pro Rata
Allocation  of the interest  portion of Special  Hazard  Losses in excess of the
Special Hazard Coverage Amount, Fraud Losses in excess of the Fraud Coverage and
Bankruptcy Losses in excess of the Bankruptcy  Coverage pursuant Section 4.03 on
such Distribution Date.
          CLASS I-R CERTIFICATE: A Certificate executed and authenticated by the
Trustee in  substantially  the form set forth in EXHIBIT B-4 and designated as a
Class I-R Certificate and evidencing an the Class R-I Component which represents
the interest  designated as a "residual interest" in REMIC I for purposes of the
REMIC  Provisions  and the Class R-II  Component  which  represents the interest
designated  as a  "residual  interest"  in REMIC II for  purposes  of the  REMIC
Provisions.
          CLASS R CERTIFICATE:  A Certificate  executed and authenticated by the
Trustee in  substantially  the form set forth in EXHIBIT B and  designated  as a
Class R  Certificate  and  evidencing  an  interest  designated  as a  "residual
interest" in the Trust REMIC for purposes of the REMIC Provisions.
          CLASS  R  INTEREST  DISTRIBUTION  AMOUNT:  On any  Distribution  Date,
one-twelfth of the product of (i) the aggregate Certificate Principal Balance of
the Class R  Certificates  as of the last day of the  related  Interest  Accrual
Period and (ii) the related Certificate Rate.
          CLASS R PRINCIPAL  DISTRIBUTION  AMOUNT: As to any Distribution  Date,
the lesser of (a) the balance of the Available  Distribution  Amount relating to
Loan Group 9 remaining  after the  distribution  of all  amounts  required to be
distributed pursuant to Section  4.02(a)(x)(i) and (b) the aggregate Certificate
Principal Balance of the Class R Certificates.
          CLASS R-I INTEREST  DISTRIBUTION  AMOUNT: On any Distribution Date and
with respect to any Class R-II Component,  (a) one-twelfth of the product of (i)
the aggregate  Certificate  Principal  Balance of the Class R-II Component as of
the last day of the related  Interest  Accrual Period and (ii) the related Class
AR5 Pass-Through  Rate,  minus (b) the aggregate  amount of Prepayment  Interest
Shortfalls  and Relief Act  Shortfalls  allocated  to such Class R-II  Component
pursuant to Section 4.05 on such Distribution Date.
                                      -12-
          CLASS  R-I  COMPONENT:  A  component  of  the  Class  I-R  Certificate
comprising the residual interest in REMIC I which will,  together with the Class
R-II Component, be represented by the Class I-R Certificate.
          CLASS  R-II  COMPONENT:  A  component  of the  Class  I-R  Certificate
comprising the residual interest in REMIC II which will, together with the Class
R-I Component, be represented by the Class I-R Certificate.
          CLASS Y CERTIFICATE: A certificate evidencing an undivided interest in
some or all of the  uncertificated  interests  relating  to the Class Y Mortgage
Loans.  If a Class Y Certificate  represents an interest in less than all of the
Class Y Regular Interests,  such certificate shall include a list of the Class Y
Mortgage  Loans in which it represents an interest and the  percentage  interest
that it  represents  in each  Class Y Regular  Interest  related to each of such
Mortgage Loans.
          CLASS Y DISTRIBUTION  AMOUNT:  With respect to each Distribution Date,
the  Available  Distribution  Amount  allocable  to the Class Y Mortgage  Loans,
subject to the exchange provisions provided in Section 6.01(b).
          CLASS Y  MORTGAGE  LOANS:  Each of the  Mortgage  Loans  listed on the
Mortgage Loan Schedule Y.
          CODE: The Internal Revenue Code of 1986.
          COMPENSATING   INTEREST:   With  respect  to  any  Distribution  Date,
calculated  separately  for the Loan Groups as a group,  the Class AR5  Mortgage
Loans and the Class Y Mortgage  Loans,  an amount  equal to interest  shortfalls
resulting from Principal  Prepayments in Full by a Mortgagor  during the related
Prepayment  Period, but not more than the lesser of (a) one-twelfth of 0.125% of
the aggregate  Principal Balance of the Mortgage,  or, with respect to the Class
AR5 Mortgage Loans and Class AR5 Certificates only,  one-twelfth of 0.25% of the
aggregate  Principal  Balance  of  the  Class  AR5  Mortgage  Loans  immediately
preceding such Distribution Date and (b) the sum of the Servicing Fee plus, with
respect to the Class AR5  Certificates  only, the Additional  Servicing Fee with
respect to the Class AR5  Mortgage  Loans to which the  Servicer  is entitled on
such  Distribution  Date,  all income and gain on amounts held in the  Custodial
Account  that  are  payable  to the  Certificateholders  with  respect  to  such
Distribution Date and any other servicing compensation to which the Servicer may
be entitled on such Distribution Date pursuant to the terms hereof.
          CORPORATE  TRUST OFFICE:  The designated  office of the Trustee in the
State of Illinois at which at any particular  time its corporate  trust business
shall  be  administered,  which  office  at the  date of the  execution  of this
Agreement  is located at ▇ ▇▇▇▇ ▇▇▇ ▇▇▇▇▇,  ▇▇▇▇▇  ▇▇▇-▇▇▇▇,  ▇▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇
▇▇▇▇▇-0481.
          CURTAILMENT: Any Principal Prepayment made by a Mortgagor which is not
a Principal Prepayment in Full.
          CUSTODIAL  ACCOUNT:  The  deposit  account  or  accounts  created  and
maintained  by the  Servicer  pursuant to Section  3.07  hereof in a  depository
institution which may be the Servicer for the benefit of the Certificateholders,
which account or accounts must be Eligible Accounts.
          CUT-OFF DATE: December 1, 1999.
                                      -13-
          DEBT SERVICE REDUCTION: With respect to any Mortgage Loan, a reduction
in the scheduled  Monthly Payment for such Mortgage Loan by a court of competent
jurisdiction in a proceeding under the Bankruptcy Code,  except such a reduction
constituting a Deficient  Valuation or any reduction that results in a permanent
forgiveness of principal.
          DEFICIENT VALUATION: With respect to any Mortgage Loan, a valuation by
a court of competent  jurisdiction  of the Mortgaged  Property in an amount less
than the then outstanding  indebtedness under the Mortgage Loan, or that results
in a permanent forgiveness of principal,  which valuation in either case results
from a proceeding under the Bankruptcy Code.
          DEFINITIVE   CERTIFICATES:   The  Class  A,  Class  R  and  Class  I-R
Certificates  and any  Certificate  issued in lieu of a  Book-Entry  Certificate
pursuant to Section 6.02(i).
          DELETED MORTGAGE LOAN: A Mortgage Loan replaced or to be replaced by a
Replacement Mortgage Loan.
          DELIVERED:  With  respect to any Eligible  Investment,  when the steps
applicable to such item as specified below are completed:
               (i) if such item is an instrument,  delivering such instrument to
the Trustee  endorsed to the Trustee or its nominee or  custodian or endorsed in
blank;
               (ii) if such item is a  certificated  security,  delivering  such
certificated security to the Trustee in bearer form or in registered form issued
to the  Trustee or  endorsed  to the  Trustee or its  nominee  or  custodian  or
endorsed in blank by an effective endorsement;
               (iii) if such item is a security  entitlement other than a United
States  Security  Entitlement,  causing a  securities  intermediary  (who  shall
maintain  the  related  financial  asset  in a  quantity  corresponding  to  the
aggregate of all security  entitlements it has established  with respect to such
financial  asset) to indicate by book entry that such security  entitlement  has
been credited to a securities account of the Trustee or its nominee or custodian
with such securities intermediary;
               (iv)  if such  item  is a  United  States  Security  Entitlement,
causing a securities  intermediary  (who shall  maintain  the related  financial
asset in a quantity  corresponding to the aggregate of all security entitlements
it has  established  with respect to such  financial  asset) to indicate by book
entry that such  United  States  Security  Entitlement  has been  credited  to a
securities  account  of the  Trustee  or its  nominee  or  custodian  with  such
securities intermediary;
               (v) if such item is a securities account,  causing the securities
intermediary to indicate by book entry that all security entitlements carried in
the securities account have been credited to such securities account; and
               (vi) if such  item is an  uncertificated  security,  causing  the
issuer of such uncertificated security to register the Trustee or its nominee or
custodian as the registered owner of such uncertificated security.
          DELIVERY DATE: December 28, 1999.
                                      -14-
          DEPOSITOR:  Credit Suisse First Boston  Mortgage  Securities  Corp., a
Delaware corporation, or its successor in interest.
          DEPOSITORY:  The  initial  Depository  shall be The  Depository  Trust
Company,  the  nominee of which is CEDE & Co., as the  registered  Holder of the
Book-Entry  Certificates.  The  Depository  shall at all  times  be a  "clearing
corporation" as defined in Section 8-102(a)(5) of the Uniform Commercial Code of
the State of New York.
          DEPOSITORY  PARTICIPANT:  A broker,  dealer,  bank or other  financial
institution  or other  Person  for whom from time to time a  Depository  effects
book-entry transfers and pledges of securities deposited with the Depository.
          DETERMINATION  DATE:  The  15th  day  (or if  such  15th  day is not a
Business Day, the Business Day immediately preceding such 15th day) of the month
of the related Distribution Date.
          DISQUALIFIED ORGANIZATION: Any organization defined as a "disqualified
organization"  under Section  860E(e)(5) of the Code,  which includes any of the
following:  (i) the United States, any State or political  subdivision  thereof,
any possession of the United States, or any agency or  instrumentality of any of
the foregoing  (other than an  instrumentality  which is a corporation if all of
its activities are subject to tax and, except for Freddie Mac, a majority of its
board of directors is not selected by such  governmental  unit),  (ii) a foreign
government, any international organization,  or any agency or instrumentality of
any of the  foregoing,  (iii) any  organization  (other  than  certain  farmers'
cooperatives  described in Section 521 of the Code) which is exempt from the tax
imposed by Chapter 1 of the Code  (including  the tax  imposed by Section 511 of
the Code on unrelated  business  taxable  income),  and(iv)  rural  electric and
telephone  cooperatives  described  in  Section  1381(a)(2)(C)  of the  Code.  A
Disqualified  Organization  also includes any "electing  large  partnership"  as
defined in Section  775(a) of the Code and any other Person so designated by the
Trustee  based  upon an  Opinion of  Counsel  that the  holding of an  ownership
interest in a Class R or Class I-R  Certificate  by such Person may cause any of
the Trust REMIC,  REMIC I or REMIC II or any Person having an ownership interest
in any Class of  Certificates  (other than such Person) to incur a liability for
any federal tax imposed  under the Code that would not  otherwise be imposed but
for the  transfer  of an  ownership  interest in a Class R  Certificate  to such
Person.  The terms "United  States,"  "State" and  "international  organization"
shall  have the  meanings  set forth in  Section  7701 of the Code or  successor
provisions.
          DISTRIBUTION  DATE: The 19th day of each month or, if such 19th day is
not a Business Day the next  succeeding  Business  Day,  commencing  in January,
1999,  with respect to the Class A and Class R  Certificates,  and commencing in
December  2001,  with  respect  to the  Class AR5  Certificates  and the Class Y
Certificates.
          DOWNGRADE  EVENT:  The date upon which the  long-term  unsecured  debt
rating of Washington Mutual is downgraded by ▇▇▇▇▇'▇ below A2.
          DUE DATE:  The first day of the  calendar  month in which the  related
Distribution Date occurs.
                                      -15-
          DUE  PERIOD:  The  period  from and  including  the  second day of the
calendar  month  preceding  the calendar  month in which any  Distribution  Date
occurs  to and  including  the  first day of the  calendar  month in which  such
Distribution Date occurs.
          ▇▇▇▇ & ▇▇▇▇▇▇:  ▇▇▇▇ & ▇▇▇▇▇▇  Credit  Rating  Co.,  or any  successor
thereto.
          ELIGIBLE ACCOUNT:  Either (i) an account or accounts maintained with a
federal or state-chartered depository institution or trust company (which may be
the  Servicer or an  affiliate of the Servicer or which may be the Trustee or an
affiliate of the Trustee) the  short-term  unsecured  debt  obligations of which
(or,  in the  case of a  depository  institution  or trust  company  that is the
principal  subsidiary  of a  holding  company,  the  short-term  unsecured  debt
obligations of such holding company) are rated not lower than P-1 in the case of
▇▇▇▇▇'▇,  A-2 in the  case of S&P  and  A-1+ in the  case  of Duff  and  ▇▇▇▇▇▇,
provided  that  so  long as  Washington  Mutual  is the  Servicer,  any  account
maintained  with the  Servicer  shall be an  Eligible  Account if the  long-term
unsecured debt obligations of Washington Mutual are rated A2 by ▇▇▇▇▇'▇, (ii) an
account  or  accounts  the  deposits  in which  are fully  insured  by the FDIC,
provided  that any such  deposits not so insured  shall be otherwise  maintained
such that (as  evidenced by an Opinion of Counsel  delivered to the Trustee) the
applicable  Certificateholders  have a claim  with  respect to the funds in such
account or a perfected first priority  security  interest against any collateral
(which  shall be limited to Eligible  Investments)  securing  such funds that is
superior  to claims of any  other  depositors  or  creditors  of the  depository
institution  or trust  company  with which such account is  maintained,  (iii) a
trust account or accounts maintained with the Trustee or the trust department of
a federal or state chartered  depository  institution or trust company acting in
its  fiduciary  capacity,  provided  that any such  state  chartered  depository
institution is subject to regulation  regarding  funds on deposit  substantially
similar  to the  regulations  set forth in 12  C.F.R.  ss.  9.10(b)  or (iv) any
account maintained at any Federal Home Loan Bank.
          ELIGIBLE  INVESTMENTS:  At any time,  any one or more of the following
obligations, instruments and securities:
               (i)  obligations  of the  United  States or any  agency  thereof,
provided such  obligations are backed by the full faith and credit of the United
States;
               (ii) general  obligations  of or  obligations  guaranteed  by any
state of the United  States or the  District of Columbia  receiving  the highest
long-term rating of ▇▇▇▇▇'▇, S&P and ▇▇▇▇ and ▇▇▇▇▇▇;
               (iii) commercial  paper (having  original  maturities of not more
than 270  days)  which is then  rated in the  highest  commercial  paper  rating
category of ▇▇▇▇▇'▇, S&P and ▇▇▇▇ and ▇▇▇▇▇▇;
               (iv)  certificates of deposit,  demand or time deposits,  federal
funds or bankers'  acceptances (in each case having  maturities of not more than
365 days) issued by any  depository  institution  or trust company  incorporated
under the laws of the  United  States or of any state  thereof  and  subject  to
supervision  and  examination  by  federal  and/or  state  banking  authorities,
provided that the commercial  paper and/or  long-term  debt  obligations of such
depository  institution  or  trust  company  (or in  the  case  of a  depository
institution  or trust  company  that is the  principal  subsidiary  of a holding
company, the commercial paper or long-term debt obligations of
                                      -16-
such holding  company) are then rated in the highest rating category of ▇▇▇▇▇'▇,
S&P and Duff and ▇▇▇▇▇▇,  in the case of  commercial  paper,  and in the highest
category  in the  case  of  long-term  debt  obligations,  and,  in the  case of
short-term debt  obligations  which have maturities of 30 days or less, a rating
of P-1 by ▇▇▇▇▇'▇, A-2 by S&P and a rating of A-1+ by ▇▇▇▇ and ▇▇▇▇▇▇;
               (v) demand or time deposits or  certificates of deposit issued by
(a) any  Federal  Home Loan  Bank or (b) any bank or trust  company  or  savings
association  which is rated at least "A" by ▇▇▇▇ and ▇▇▇▇▇▇  which has  combined
capital,  surplus  and  undistributed  profits of not less than $50  million and
fully insured by the FDIC;
               (vi)  repurchase   obligations   with  respect  to  any  security
described in (i) and (ii) above or any other security issued or guaranteed by an
agency or instrumentality of the United States, in either case entered into with
a depository  institution  or trust company  (acting as principal)  described in
(iv) above;
               (vii) securities bearing interest or sold at a discount issued by
any  corporation  incorporated  under the laws of the United States or any state
thereof  which,  at the  time  of  such  investment  or  contractual  commitment
providing for such  investments are then rated in the highest rating category of
▇▇▇▇▇'▇, S&P and ▇▇▇▇ and ▇▇▇▇▇▇; and
               (viii)  units of  taxable  money-market  portfolios  rated in the
highest rating  category by ▇▇▇▇▇'▇,  S&P and Duff and ▇▇▇▇▇▇ and not restricted
to  obligations  issued or  guaranteed by any agency or  instrumentality  of the
United  States or entities  whose  obligations  are backed by the full faith and
credit of the United States and  repurchase  agreements  collateralized  by such
obligations.
PROVIDED  that (A) such  obligation  or security is held for a temporary  period
pursuant  to  Treasury  Regulations  Section  1.860G-2(g)(1),  and (B)  Eligible
Investments  shall include only such  obligations or securities that are payable
on demand or mature on or before the (i) Business Day immediately  preceding the
next  Distribution  Date with  respect to amounts on deposit in the  Certificate
Account  and  (ii)  the  second  Business  Day  immediately  preceding  the next
Distribution  Date with respect to amounts on deposit in the Custodial  Account.
In  addition,  no Eligible  Investment  which  incorporates  a penalty for early
withdrawal will be used unless the maturity of such Eligible Investment is on or
before the Business Day immediately preceding the next Distribution Date.
          ESCROW ACCOUNT: As defined in Section 3.08 hereof.
          EVENT OF DEFAULT: As defined in Section 8.01 hereof.
          ▇▇▇▇▇▇ ▇▇▇: The Federal  National  Mortgage  Association,  a federally
chartered  and privately  owned  corporation  organized  and existing  under the
Federal National Mortgage Association Charter Act, or any successor thereto.
          FDIC:  The Federal  Deposit  Insurance  Corporation,  or any successor
thereto.
          FINAL  DISTRIBUTION  DATE:  The  Distribution  Date on which the final
distribution  in respect of the  Certificates  will be made  pursuant to Section
10.01,  which Final Distribution Date shall in no event be later than the end of
the 90-day liquidation period described in Section 10.03.
                                      -17-
          FRAUD  COVERAGE:  During the period prior to the first  anniversary of
the Class AR5 Cut-off  Date,  2.00% of the  aggregate  principal  balance of the
Class AR5 Mortgage Loans as of the Cut-off Date (the "Initial Fraud  Coverage"),
reduced by Fraud Losses  allocated to the Class AR Certificates  since the Class
AR5 Cut-off Date;  during the period from the first anniversary of the Class AR5
Cut-off  Date to (but not  including)  the  fifth  anniversary  of the Class AR5
Cut-off  Date,  the amount of the Fraud  Coverage  on the most  recent  previous
anniversary  of the Class AR5 Cut-off Date  (calculated  in accordance  with the
second  sentence of this  definition)  reduced by Fraud Losses  allocated to the
Class AR5  Certificates  since  such  anniversary;  and during the period on and
after the fifth  anniversary of the Cut-off Date,  zero. On each  anniversary of
the Class AR5 Cut-off Date, the Fraud Coverage shall be reduced to the lesser of
(i) on the  first,  second,  third  and  fourth  anniversaries  of the Class AR5
Cut-off Date, 1.00% of the aggregate  principal balance of the Mortgage Loans as
of the Due Date in the preceding  month and (ii) the excess of the Initial Fraud
Coverage over cumulative  Fraud Losses  allocated to the Class AR5  Certificates
since the Class AR5 Cut-off Date.
          The Fraud Coverage may be reduced upon written  confirmation  from the
Rating  Agencies that such reduction will not adversely  affect the then current
ratings assigned to the Certificates by the Rating Agencies.
          FRAUD LOSS:  A Realized  Loss (or portion  thereof)  with respect to a
Mortgage  Loan arising from any action,  event or state of facts with respect to
such  Mortgage  Loan that  involved or arose out of any  dishonest,  fraudulent,
criminal,  negligent  or  knowingly  wrongful  act,  error  or  omission  by the
Mortgagor,  originator (or assignee  thereof) of such Mortgage Loan, an owner of
the Mortgage Loan or any servicer in connection with the origination thereof.
          FREDDIE MAC: The Federal Home Loan Mortgage  Corporation,  a corporate
instrumentality of the United States created and existing under Title III of the
Emergency Home Finance Act of 1970, as amended, or any successor thereto.
          GROUP 1 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-1. The Group 1 Loans relate to the Class
A-1 Certificates.
          GROUP 2 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-2. The Group 2 Loans relate to the Class
A-2 Certificates.
          GROUP 3 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-3. The Group 3 Loans relate to the Class
A-3 Certificates.
          GROUP 4 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-4. The Group 4 Loans relate to the Class
A-4 Certificates.
          GROUP 5 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-5. The Group 5 Loans relate to the Class
A-5 Certificates.
          GROUP 6 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-6. The Group 6 Loans relate to the Class
A-6 Certificates.
          GROUP 7 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-7. The Group 7 Loans relate to the Class
A-7 Certificates.
                                      -18-
          GROUP 8 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-8. The Group 8 Loans relate to the Class
A-8 Certificates.
          GROUP 9 LOANS:  The Mortgage  Loans  designated  on the Mortgage  Loan
Schedule  attached  hereto as Exhibit C-9. The Group 9 Loans relate to the Class
A-9 and Class R Certificates.
          INDEX:  With respect to each  Mortgage Loan that does not bear a fixed
Mortgage Rate, either the One-Year CMT Index or the One-Year MTA Index.
          INITIAL CERTIFICATE  PRINCIPAL BALANCE:  With respect to each Class of
Certificates, the Certificate Principal Balance of such Class of Certificates or
interests  as of the  Cut-off  Date as set  forth in the  Preliminary  Statement
hereto.
          INSURANCE PROCEEDS: Amounts paid pursuant to any insurance policy with
respect  to a  Mortgage  Loan  that have not been used to  restore  the  related
property.
          INTEREST ACCRUAL PERIOD:  With respect to any  Distribution  Date, the
calendar month preceding such Distribution Date.
          LIQUIDATED  LOAN:  With respect to any  Distribution  Date, a Mortgage
Loan which,  as of the close of business on the Business Day next  preceding the
related  Determination  Date,  (a) has been  liquidated  through deed in lieu of
foreclosure,  sale in  foreclosure,  trustee's  sale  or  other  realization  as
provided by applicable law of real property  subject to the related Mortgage and
any security  agreements  or (b) with  respect to which  payment  under  related
private  mortgage  insurance  or  hazard  insurance  and/or  from any  public or
governmental  authority  on  account  of a taking  or  condemnation  of any such
property has been received;  PROVIDED,  HOWEVER, that any REO Property shall not
be treated as a Liquidated Loan until such property has been finally liquidated.
          LIQUIDATION  EXPENSES:   Customary  and  reasonable  "out  of  pocket"
expenses  incurred by the Servicer (or the related  Sub-Servicer)  in connection
with the  liquidation  of any  defaulted  Mortgage Loan and not recovered by the
Servicer (or the related Sub-Servicer) under a Primary Mortgage Insurance Policy
for  reasons  other than the  Servicer's  failure to comply  with  Section  3.10
hereof,  such expenses including,  without limitation,  legal fees and expenses,
any unreimbursed amount expended by the Servicer pursuant to Section 3.11 hereof
respecting the related  Mortgage and any related and  unreimbursed  expenditures
for real estate  property taxes or for property  restoration or  preservation to
the extent not  previously  reimbursed  under any  hazard  insurance  policy for
reasons other than the Servicer's failure to comply with Section 3.11 hereof.
          LIQUIDATION  PROCEEDS:  Amounts other than Insurance Proceeds received
in connection with the liquidation of a defaulted Mortgage Loan, whether through
trustee's sale,  foreclosure sale or otherwise or amounts received in connection
with any condemnation or partial release of a Mortgaged Property.
          LOAN  GROUP:  Any or all of the Loan Group 1, Loan Group 2, Loan Group
3, Loan Group 4, Loan Group 5, Loan Group 6, Loan Group 7, Loan Group 8 and Loan
Group 9.
          LOAN GROUP 1: The group of  Mortgage  Loans  comprised  of the Group 1
Loans.
          LOAN GROUP 2: The group of  Mortgage  Loans  comprised  of the Group 2
Loans.
                                      -19-
          LOAN GROUP 3: The group of  Mortgage  Loans  comprised  of the Group 3
Loans.
          LOAN GROUP 4: The group of  Mortgage  Loans  comprised  of the Group 4
Loans.
          LOAN GROUP 5: The group of  Mortgage  Loans  comprised  of the Group 5
Loans.
          LOAN GROUP 6: The group of  Mortgage  Loans  comprised  of the Group 6
Loans.
          LOAN GROUP 7: The group of  Mortgage  Loans  comprised  of the Group 7
Loans.
          LOAN GROUP 8: The group of  Mortgage  Loans  comprised  of the Group 8
Loans.
          LOAN GROUP 9: The group of  Mortgage  Loans  comprised  of the Group 9
Loans.
          LOAN-TO-VALUE  RATIO:  As of any date,  the  fraction,  expressed as a
percentage,  the  numerator  of which is the  Principal  Balance of the  related
Mortgage Loan at the date of  determination  and the denominator of which is the
Appraised  Value  of  the  related  Mortgaged  Property  or,  in the  case  of a
Replacement Mortgage Loan, the appraised value of the related Mortgaged Property
as of the date of its origination.
          MARGIN:  As to each Mortgage Loan that does not bear a fixed  Mortgage
Rate,  the  fixed  percentage  set forth in the  related  Mortgage  Note,  which
percentage is added to the applicable Index on each Adjustment Date to determine
(subject  to  rounding  in  accordance  with  the  related  Mortgage  Note,  the
applicable  Periodic Cap,  Maximum  Interest Rate and Minimum Interest Rate) the
interest rate to be borne by such Mortgage Loan until the next  Adjustment  Date
thereof.
          MATURITY DATE: The latest possible  maturity date, solely for purposes
of  Section  1.860G-1(a)(4)(iii)  of the  Treasury  regulations,  by  which  the
Certificate  Principal  Balance,  if any, of each Class of Regular  Certificates
would be reduced  to zero as  determined  under a  hypothetical  scenario  which
assumes  that such date is the  Distribution  Date in the month of the  maturity
date of the Mortgage Loan with the latest scheduled  maturity date. The Maturity
Date for each Class of Regular  Certificates is the Distribution  Date occurring
in November 2039.
          MAXIMUM  INTEREST  RATE:  As to any Mortgage Loan that does not bear a
fixed  Mortgage  Rate,  the  maximum  interest  rate  that  may be borne by such
Mortgage  Loan as set forth in the  related  Mortgage  Note,  which  rate may be
applicable  to such  Mortgage  Loan at any time during the life of such Mortgage
Loan.
          MINIMUM  INTEREST  RATE:  As to any Mortgage Loan that does not bear a
fixed  Mortgage  Rate,  the  minimum  interest  rate  that  may be borne by such
Mortgage  Loan as set forth in the  related  Mortgage  Note,  which  rate may be
applicable  to such  Mortgage  Loan at any time during the life of such Mortgage
Loan.
          MONTHLY  ADVANCE:  With  respect  to Loan  Group 5, Loan Group 6, Loan
Group 7, Loan Group 8, Loan Group 9, the Class AR5 Mortgage  Loans and the Class
Y Mortgage  Loans,  the  aggregate of the  advances  made by or on behalf of the
Servicer with respect to any  Distribution  Date pursuant to Section 5.01 hereof
relating to the Mortgage Loans in such Loan Group,  the Class AR5 Mortgage Loans
or the Class Y Mortgage  Loans,  the amount of any such advances  being equal to
the  regular  monthly  installments  of  principal  and  interest on the related
Mortgage Loans
                                      -20-
that were due on the related Due Date and delinquent as of the close of business
on the related  Determination  Date, after adjustment of any delinquent interest
payment  to be equal to  interest  at a rate equal to the Net  Mortgage  Rate or
Class AR5 Net Mortgage Rate, in the case of the Class AR5 Mortgage Loans, on the
Principal  Balance of such Mortgage Loans, less the aggregate amount of any such
delinquent  payments  that  the  Servicer  has  determined  would  constitute  a
Nonrecoverable Advance if made.
          MONTHLY  PAYMENT:  The  scheduled  monthly  payment of  principal  and
interest on a Mortgage Loan.
          MOODY'S: ▇▇▇▇▇'▇ Investors Service, Inc. or any successor thereto.
          MORTGAGE:  The mortgage,  deed of trust or other instrument creating a
first  lien on a fee  simple or  leasehold  estate in real  property  securing a
Mortgage Note.
          MORTGAGE FILE:  For each Mortgage Loan, the Trustee  Mortgage File and
the Servicer Mortgage File.
          MORTGAGE LOAN: Each of the mortgage loans  transferred and assigned to
the Trustee pursuant to the provisions hereof as from time to time are held as a
part of the Trust Fund,  evidenced by a Mortgage Note and secured by a Mortgage,
the mortgage loans so held being  identified in the Mortgage Loan  Schedule,  as
amended from time to time.
          MORTGAGE LOAN PURCHASE AGREEMENT: The Mortgage Loan Purchase Agreement
dated as of December 1, 1999 between the  Depositor,  Credit Suisse First Boston
Corporation  and the  Seller,  pursuant  to which the  Depositor  purchased  the
Mortgage Loans from the Seller.
          MORTGAGE LOAN REPURCHASE PRICE: The price,  calculated as set forth in
Section  10.01(a),  to be paid in connection with the repurchase of the Mortgage
Loans pursuant to an Optional Termination of the Trust Fund.
          MORTGAGE LOAN SCHEDULE:  The list of Mortgage Loans transferred to the
Trustee  as part of the Trust  Fund for the  Certificates  and from time to time
subject  to this  Agreement  (as from time to time  amended by the  Servicer  to
reflect the addition of  Replacement  Mortgage Loans and the deletion of Deleted
Mortgage Loans pursuant to the provisions of this Agreement), attached hereto as
EXHIBIT C-1 (with  respect to the Group 1 Loans),  EXHIBIT C-2 (with  respect to
the Group 2 Loans), EXHIBIT C-3 (with respect to the Group 3 Loans), EXHIBIT C-4
(with  respect to the Group 4 Loans),  EXHIBIT C-5 (with  respect to the Group 5
Loans),  EXHIBIT  CE-6 (with  respect to the Group 6 Loans),  EXHIBIT  C-7 (with
respect to the Group 7 Loans),  EXHIBIT C-8 (with  respect to the Group 8 Loans)
and EXHIBIT C-9 (with respect to the Group 9 Loans), setting forth the following
information with respect to each Mortgage Loan:
               (i) the loan number;
               (ii) the city, state and zip code for each Mortgaged Property;
               (iii) the applicable Index;
               (iv) the Margin, if applicable;
               (v) the Maximum Interest Rate, if applicable;
                                      -21-
               (vi) the Minimum Interest Rate, if applicable;
               (vii) the original term to maturity;
               (viii) the remaining term to maturity as of the Cut-off Date;
               (ix) the original principal balance;
               (x)  the Principal Balance as of the Cut-off Date;
               (xi) the first Due Date;
               (xii) the Monthly Payment in effect as of the Cut-off Date;
               (xiii) the Loan-to-Value Ratio at origination;
               (xiv) the Appraised Value of the Mortgaged Property;
               (xv) the Net Mortgage Rate as of the Cut-off Date;
               (xvi) the next Adjustment Date, if applicable;
               (xvii) the initial Adjustment Date, if applicable;
               (xviii) the Mortgage Rate as of the Cut-off Date, if applicable;
               (xix)a code indicating  whether the Mortgaged  Property is either
(a) a detached  single-family dwelling or a de minimis planned unit development,
(b) a  condominium  unit or a dwelling in a planned unit  development,  or (c) a
two- to four-family residential property;
               (xx) a code indicating whether the Mortgaged Property at the time
of origination was represented to be owner-occupied; and
               (xxi) the purpose for which the financing was made.
Such schedule shall also set forth the total of the amounts described under (ix)
above for all of the Mortgage  Loans.  Such  schedule may be in the form of more
than one list  collectively  setting forth all of the  information  required and
shall also be in a computer-readable format acceptable to the Trustee.
          MORTGAGE  LOAN  SCHEDULE  X: The list of  Mortgage  Loans  attached as
Exhibit X and part of the Trust  Fund for the  Class AR5  Certificates  and from
time to time  subject  to this  Agreement  (as from time to time  amended by the
Servicer to reflect the addition of Replacement  Mortgage Loans and the deletion
of Deleted Mortgage Loans pursuant to the provisions of this  Agreement),  (with
respect  to  the  Class  AR5  Mortgage  Loans),   setting  forth  the  following
information with respect to each Mortgage Loan:
               (i) the loan number;
               (ii) the city, state and zip code for each Mortgaged Property;
               (iii) the applicable Index;
               (iv) the Margin;
               (v) the Maximum Interest Rate;
               (vi) the Minimum Interest Rate;
               (vii) the original term to maturity;
                                      -22-
               (viii) the remaining term to maturity as of the Class AR5 Cut-off
Date;
               (ix) the original principal balance;
               (x) the Principal Balance as of the Class AR5 Cut-off Date;
               (xi) the first Due Date;
               (xii) the  Monthly  Payment in effect as of the Class AR5 Cut-off
Date;
               (xiii) the Loan-to-Value Ratio at origination;
               (xiv) the Appraised Value of the Mortgaged Property;
               (xv) the Class AR5 Net Mortgage  Rate as of the Class AR5 Cut-off
Date;
               (xvi) the next  Adjustment  Date  following the Class AR5 Cut-off
Date;
               (xvii) the initial Adjustment Date;
               (xviii) the Mortgage Rate as of the Class AR5 Cut-off Date;
               (xix) a code indicating  whether the Mortgaged Property is either
(a) a detached  single-family dwelling or a de minimis planned unit development,
(b) a  condominium  unit or a dwelling in a planned unit  development,  or (c) a
two- to four-family residential property;
               (xx) a code indicating whether the Mortgaged Property at the time
of origination was represented to be owner-occupied; and
               (xxi) the purpose for which the financing was made.
Such schedule shall also set forth the total of the amounts  described under (x)
above for all of the Class AR5 Mortgage Loans.  Such schedule may be in the form
of more than one list collectively setting forth all of the information required
and shall also be in a computer-readable format acceptable to the Trustee.
          MORTGAGE  LOAN  SCHEDULE  Y: The list of  Mortgage  Loans  attached as
Exhibit Y and part of the Trust Fund for the Class Y Certificates  and from time
to time subject to this  Agreement (as from time to time amended by the Servicer
to reflect  the  addition  of  Replacement  Mortgage  Loans and the  deletion of
Deleted  Mortgage  Loans pursuant to the  provisions of this  Agreement),  (with
respect to the Class Y Mortgage Loans),  setting forth the following information
with respect to each Mortgage Loan:
               (i) the loan number;
               (ii) the city, state and zip code for each Mortgaged Property;
               (iii) the applicable Index;
               (iv) the Margin;
               (v) the Maximum Interest Rate;
               (vi) the Minimum Interest Rate;
               (vii) the original term to maturity;
               (viii) the remaining term to maturity as of the Class AR5 Cut-off
Date;
               (ix) the original principal balance;
                                      -23-
               (x) the Principal Balance as of the Class AR5 Cut-off Date;
               (xi) the first Due Date;
               (xii) the  Monthly  Payment in effect as of the Class AR5 Cut-off
Date;
               (xiii) the Loan-to-Value Ratio at origination;
               (xiv) the Appraised Value of the Mortgaged Property;
               (xv) the Net Mortgage Rate as of the Class AR5 Cut-off Date;
               (xvi) the next  Adjustment  Date  following the Class AR5 Cut-off
Date;
               (xvii) the initial Adjustment Date;
               (xviii) the Mortgage Rate as of the Class AR5 Cut-off Date;
               (xix) a code indicating  whether the Mortgaged Property is either
(a) a detached  single-family dwelling or a de minimis planned unit development,
(b) a  condominium  unit or a dwelling in a planned unit  development,  or (c) a
two- to four-family residential property;
               (xx) a code indicating whether the Mortgaged Property at the time
of origination was represented to be owner-occupied; and
               (xxi) the purpose for which the financing was made.
Such schedule shall also set forth the total of the amounts  described under (x)
above for all of the Class Y Mortgage Loans. Such schedule may be in the form of
more than one list  collectively  setting forth all of the information  required
and shall also be in a computer-readable format acceptable to the Trustee.
          MORTGAGE  NOTE:  The original  executed note or other  evidence of the
indebtedness  of a  Mortgagor  under a  Mortgage  Loan,  including  a lost  note
affidavit with a copy of the related note.
          MORTGAGE  RATE:  The annual rate of interest borne by a Mortgage Note,
which is set forth in the related  Mortgage  Note.  The  Mortgage  Rate for each
Mortgage  Loan that is not a fixed  Mortgage Rate as of the Cut-off Date will be
adjusted  on each  Adjustment  Date  to a rate  equal  to the  sum of the  Index
applicable  to such  Adjustment  Date and the  Margin,  rounded  to or up to the
nearest multiple of 0.125%,  as specified in the related Mortgage Note,  subject
to the  application of the applicable  Periodic Cap,  Maximum  Interest Rate and
Minimum Interest Rate.
          MORTGAGED PROPERTY: The underlying property securing a Mortgage Loan.
          MORTGAGOR: Each obligor on a Mortgage Note.
          NET  MORTGAGE  RATE:  As to each  Mortgage  Loan,  with respect to any
Distribution  Date, a rate per annum equal to (a) the Mortgage Rate in effect as
of the Due Date in the  preceding  calendar  month minus (b) the  Servicing  Fee
Rate.
          1933 ACT: The Securities Act of 1933, as amended.
          1934 ACT: The Securities Exchange Act of 1934, as amended.
                                      -24-
          NONRECOVERABLE  ADVANCE:  The  portion of any  Monthly  Advance or any
other advance  previously  made or proposed to be made by the Servicer  that, in
the good faith  judgment of the Servicer,  will not or, in the case of a current
delinquency, would not be, ultimately recoverable by the Servicer from Insurance
Proceeds or Liquidation  Proceeds (net of Liquidation  Expenses) with respect to
the related Mortgage Loan.
          OFFICERS'  CERTIFICATE:  A  certificate  signed by the Chairman of the
Board,  any Vice Chairman of the Board,  the President,  a Group  President,  an
Executive  Vice  President,  a Senior  Executive  Vice  President,  Senior  Vice
President, a Vice President,  or other authorized officer, and by the Treasurer,
the Secretary, or one of the Assistant Vice Presidents,  Assistant Treasurers or
Assistant Secretaries of the Depositor, the Seller, the Servicer or the Trustee,
as the case may be, and delivered to the Depositor,  the Seller, the Servicer or
the Trustee, as required by this Agreement.
          ONE-YEAR CMT INDEX: A per annum rate equal to the weekly average yield
on U.S.  Treasury  securities  adjusted  to a constant  maturity  of one year as
reported by the Federal Reserve Board in statistical Release No. H.15(519) as of
the date  specified  in the related  Mortgage  Note,  or, in the event that such
index is no longer  available,  an index selected by the Servicer and reasonably
acceptable to the Trustee that is based on comparable information.
          ONE-YEAR MTA INDEX: A per annum rate equal to the twelve-month average
of the annual yields on U.S. Treasury securities adjusted to a constant maturity
of one year as reported  by the  Federal  Reserve  Board  yields in  statistical
release entitled "Selected  Interest  Rates-G13" which is published on the first
Tuesday of each  month or, in the event that such index is no longer  available,
an index selected by the Servicer and reasonably  acceptable to the Trustee that
is based on comparable information.
          OPINION OF COUNSEL:  A written opinion of counsel,  who may be counsel
for the Depositor or the Servicer,  reasonably  acceptable to the Trustee.  With
respect to any opinion  dealing with the definition of Eligible  Account in this
Article I, Sections 2.04 or 7.04 hereof or with the  qualification of a REMIC or
compliance  with  the  REMIC  Provisions,  such  counsel  must  (i) in  fact  be
independent  of the  Depositor  and the  Servicer,  (ii)  not  have  any  direct
financial  interest in the  Depositor  or the  Servicer or in any  affiliate  of
either of them and (iii) not be connected  with the Depositor or the Servicer as
an officer,  employee,  promoter,  underwriter,  trustee,  partner,  director or
Person performing similar functions.
          OPTIONAL  TERMINATION:  The purchase of the Mortgage Loans pursuant to
Section 10.01(a).
          OPTIONAL  TERMINATION  DATE:  The date fixed by the  Servicer  for the
purchase of the Mortgage Loans pursuant to Section 10.01(a).
          OUTSTANDING MORTGAGE LOAN: As to any date of determination, a Mortgage
Loan  (including  an REO  Property)  which was not the  subject  of a  Principal
Prepayment  in Full,  Cash  Liquidation  or REO  Disposition  and  which was not
purchased,  deleted  or  substituted  for  prior to such  date of  determination
pursuant to Section 2.02 or 2.04.
          PASS-THROUGH  ENTITY: (a) a regulated  investment company described in
Section 851 of the Code, a real estate investment trust described in Section 856
of the Code, a common trust
                                      -25-
fund or an  organization  described  in  Section  1381(a)  of the Code,  (b) any
partnership,  trust or estate or (c) any person holding a Class A Certificate as
nominee for another person.
          PERCENTAGE  INTEREST:  The percentage interest (which may be expressed
as a fraction) evidenced by any Certificate, which (a) in the case of each Class
of  the  Class  A  and  Class  AR5  Certificates   (other  than  the  Class  I-R
Certificates),  is equal to a fraction,  the  numerator  of which is the Initial
Certificate Principal Balance of such Certificate,  and the denominator of which
is  equal  to  the  aggregate  Initial  Certificate  Principal  Balances  of all
Certificates of the same Class and (b) in the case of each the Class R and Class
I-R Certificates, is set forth on the face thereof.
          PERIODIC  CAP: With respect to each Mortgage Loan that does not bear a
fixed Mortgage  Rate,  the maximum  increase or decrease in the Mortgage Rate on
any Adjustment Date, as specified in the related Mortgage Note.
          PERSON:  Any  individual,  corporation,  partnership,  joint  venture,
association,   joint-stock  company,  trust,   unincorporated   organization  or
government, or any agency or political subdivision thereof.
          PREPAYMENT DISTRIBUTION  PERCENTAGE:  With respect to any Distribution
Date and the Class B  Certificates  with the highest  payment  priority and each
other Class of Class B Certificates  that satisfies the Prepayment  Distribution
Trigger, such class's pro rata share, based on the Certificate Principal Balance
of such  Class  relative  to the  Certificate  Principal  Balance of the Class B
Certificates  with the highest payment  priority and each other Class of Class B
Certificates that satisfied the Prepayment Distribution Trigger.
          PREPAYMENT DISTRIBUTION TRIGGER: With respect to any Distribution Date
and any Class of Class B  Certificates,  a test that shall be  satisfied  if the
fraction  (expressed  as a  percentage)  equal  to the  sum  of the  Certificate
Principal  Balances of such Class of Certificates and each Class of Certificates
with a lower  payment  priority  immediately  prior  to such  Distribution  Date
divided by the  aggregate  Principal  Balance  (or  related  real  estate  owned
properties) immediately prior to such Distribution Date is greater than or equal
to such percentage as of the Closing Date.
          PREPAYMENT  INTEREST  SHORTFALL:  As to any Distribution  Date and any
Mortgage Loan (other than a Mortgage  Loan secured by an REO Property)  that was
the subject of a Principal  Prepayment  during the related  Prepayment Period by
the Mortgagor,  an amount equal to the excess of (a) one month's interest at the
Mortgage Rate on the Principal  Balance of such Mortgage Loan before taking into
account such Principal Prepayment over (b) the sum of (i) the amount of interest
paid by the Mortgagor for such  Prepayment  Period to the date of such Principal
and (ii) the Compensating  Interest payable by the Servicer on such Distribution
Date with respect to such Mortgage Loan.
          PREPAYMENT PERIOD: With respect to any Distribution Date, the calendar
month prior to the month in which such Distribution Date occurs.
          PRIMARY  MORTGAGE  INSURANCE  POLICY:  Each primary policy of mortgage
guaranty  insurance with respect to the Mortgage Loans or any replacement policy
therefor.
          PRINCIPAL  BALANCE:  With respect to any Mortgage Loan, as of the date
of any  determination,  the principal balance of such Mortgage Loan remaining to
be paid by the Mortgagor
                                      -26-
as of the Cut-off  Date after  deduction  of all  payments  due on or before the
Cut-off  Date,  reduced  (but  not  below  zero)  by the sum of (i) all  amounts
previously received or collected by the Servicer in respect of principal of such
Mortgage Loan  subsequent to the Cut-off Date,  other than amounts  representing
payments due on such  Mortgage  Loan on or prior to the Cut-off  Date;  (ii) all
Liquidation  Proceeds  (net of  Liquidation  Expenses)  and  Insurance  Proceeds
allocated to  principal;  (iii) all amounts  allocable to the  principal of such
Mortgage Loan previously paid by the Servicer as part of a Monthly  Advance,  in
each case which were distributed to Certificateholders pursuant to Section 4.02;
and (iv) all  Realized  Losses  allocated  to  Certificateholders  with  respect
thereto on any previous Distribution Date. In the case of a Replacement Mortgage
Loan,  "Principal  Balance"  shall mean, at the time of any  determination,  the
principal balance of such Replacement  Mortgage Loan on the date of substitution
after  deduction  of all  payments due on or before the Due Date in the month of
substitution,  reduced by the sums described in (i) through (iv),  above,  after
such Due Date.
          PRINCIPAL  PREPAYMENT:  Any  Mortgagor  payment or other  recovery  of
principal  on a  Mortgage  Loan,  including  a  recovery  that takes the form of
Liquidation  Proceeds or Insurance Proceeds,  that is received in advance of its
scheduled  Due  Date  and  is  not  accompanied  by an  amount  as  to  interest
representing  scheduled interest due on any date or dates in any month or months
subsequent to the month of prepayment.
          PRINCIPAL  PREPAYMENT  IN FULL:  Any  Principal  Prepayment  made by a
Mortgagor of the Principal Balance of a Mortgage Loan.
          PRO RATA  ALLOCATION:  With respect to the allocation of the principal
portion of Special Hazard Losses in excess of the Special Hazard Coverage, Fraud
Losses in excess of the Fraud  Coverage and  Bankruptcy  Losses in excess of the
Bankruptcy  Coverage  among the Class AR5  Certificates,  a pro rata  allocation
according  to their  respective  Certificate  Principal  Balances  in  reduction
thereof,  and with respect to the  allocation  of the  interest  portion of such
Realized  Losses  among  the  Class  AR5  Certificates,  a pro  rata  allocation
according  to the amount of  interest  accrued but unpaid on each such Class for
the related Interest Accrual Period, in reduction thereof.
          PURCHASE  PRICE:  With  respect to any  Mortgage  Loan  required to be
purchased by the Seller or Servicer  pursuant to Section 2.01,  2.02, 2.03, 2.04
or 3.12 the sum of (i) 100% of the Principal Balance of the Mortgage Loan on the
date of such purchase,  (ii) accrued and unpaid interest to the next Due Date on
the Mortgage  Loan at a rate equal to the Net Mortgage Rate or the Class AR5 Net
Mortgage Rate, in the case of a Class AR5 Mortgage Loan, and (iii) the amount of
any  unreimbursed  Monthly Advances and other advances made by the Servicer with
respect  to such  Mortgage  Loan and  reimbursable  to the  Servicer  hereunder;
provided, however, that if the Servicer shall so choose, the Purchase Price with
respect to any  Mortgage  Loan  purchased by the Servicer may be net of advances
that would otherwise be reimbursable to the Servicer and the Servicer shall have
no further  entitlement to reimbursement for such advances.  With respect to any
Mortgage Loan required or allowed to be  purchased,  the Servicer or Seller,  as
applicable,  shall  deliver to the Trustee an  Officers'  Certificate  as to the
calculation of the Purchase Price.
          QUALIFIED   INSURER:   A  mortgage  guaranty  insurance  company  duly
qualified as such under the laws of the state of its principal place of business
and each other state having  jurisdiction  over such insurer in connection  with
the insurance policy issued by such insurer, duly authorized and licensed by the
insurance  regulatory  authority of the state of its principal place of business
and,
                                      -27-
to the extent  required by applicable  law, each such other state, to transact a
mortgage guaranty insurance business in such state and each such other state and
to write  the  insurance  provided  by the  insurance  policy  issued  by it and
approved  as an  insurer by  Freddie  Mac or ▇▇▇▇▇▇ ▇▇▇ and whose  claims-paying
ability will not adversely affect the then current rating on the Certificates.
          RATING AGENCIES: ▇▇▇▇▇'▇ & S&P.
          REALIZED  LOSS: An amount  determined by the Servicer and evidenced by
an  Officers'  Certificate  delivered  to the Trustee,  in  connection  with any
Mortgage Loan equal to (a) with respect to any  Liquidated  Loan,  the excess of
the Principal  Balance of such Liquidated  Loan plus interest  thereon at a rate
equal to the applicable Net Mortgage Rate or Class AR5 Net Mortgage Rate, in the
case of a Class AR5 Mortgage  Loan,  from the Due Date as to which  interest was
last paid up to the Due Date next succeeding such liquidation over proceeds,  if
any,  received in connection  with such  liquidation,  after  application of all
withdrawals  permitted  to be made by the  Servicer  from the related  Custodial
Account with  respect to such  Mortgage  Loan,  (b) with respect to any Mortgage
Loan which has become the  subject of a Deficient  Valuation,  the excess of the
Principal  Balance of the Mortgage Loan over the principal  amount as reduced in
connection with the proceedings  resulting in the Deficient Valuation,  (c) with
respect to any  Mortgage  Loan which has  become the  subject of a Debt  Service
Reduction,  the present  value of all monthly  Debt Service  Reductions  on such
Mortgage  Loan,  assuming  that the Mortgagor  pays each Monthly  Payment on the
applicable Due Date and that no Principal  Prepayments are received with respect
to such Mortgage Loan, discounted monthly at the applicable Mortgage Rate or (d)
the amount of any  reduction  by the Servicer to the  principal  balance of such
Mortgage Loan pursuant to Section 3.01 hereof.
          RECORD  DATE:  With  respect to any  Distribution  Date,  the close of
business on the last Business Day of the month  preceding the month in which the
applicable  Distribution Date occurs provided however,  that with respect to the
Distribution  Date  occurring  in January  2000,  the  Record  Date shall be the
Delivery Date and for the Class AR5  Certificates  and the Class Y  Certificates
with respect to the Distribution  Date falling in December 2001, the Record Date
shall be the Class AR5 Delivery Date.
          REGULAR  CERTIFICATES:  All of the Certificates other than the Class R
and Class I-R Certificates.
          RELIEF ACT: The  Soldiers'  and Sailors'  Civil Relief Act of 1940, as
amended.
          RELIEF ACT SHORTFALLS:  With respect to any Distribution  Date and any
Mortgage  Loan,  the amount of any  interest  that is not  collectible  from the
Mortgagor  during the related  Due Period  pursuant to the Relief Act or similar
legislation or regulations as in effect from time to time.
          REMIC: A "real estate mortgage investment conduit," within the meaning
of Section 860D of the Code.
          REMIC ELECTION: An election, for federal income tax purposes, to treat
certain assets as a REMIC.
          REMIC  REGULAR  INTEREST:  Any  of  the  Class  A  Certificates,  each
uncertificated   interest   representing  a  Class  AR5  Mortgage   Loan,   each
uncertificated  interest  representing a Class Y Mortgage Loan and the Class AR5
Certificates.
                                      -28-
          REMIC PROVISIONS: Provisions of the federal income tax law relating to
REMIC,  which appear at Section 860A through 860G of the Subchapter M of Chapter
1 of the Code and related provisions, and regulations promulgated thereunder, as
the foregoing may be in effect from time to time.
          REMIC I: The  corpus of the Trust  Fund  consisting  of the Class A-1,
Class A-2,  Class A-3 and Class A-4  Certificates,  as to which a REMIC election
will be made pursuant to the provisions  hereof, and having regular and residual
interests as provided herein.
          REMIC I REGULAR  INTERESTS:  As defined in the  Preliminary  Statement
hereto.
          REMIC II: The corpus of the Trust Fund consisting of Class AR5 Regular
Interests,  as to which a REMIC election will be made pursuant to the provisions
hereof, and having regular and residual interests as provided herein.
          REO  ACQUISITION:  The  acquisition  by the  Servicer on behalf of the
Trustee for the benefit of the  Certificateholders  of any REO Property pursuant
to Section 3.13.
          REO  DISPOSITION:  As to any  REO  Property,  a  determination  by the
Servicer that it has received all Insurance Proceeds,  Liquidation Proceeds, REO
Proceeds and other payments and recoveries  (including proceeds of a final sale)
which the  Servicer  expects  to be finally  recoverable  from the sale or other
disposition of the REO Property.
          REO PROPERTY: Any Mortgaged Property acquired by or in the name of the
Trustee  for  the  benefit  of  the  Certificateholders  in  foreclosure  or  by
deed-in-lieu of foreclosure.
          REO PROCEEDS:  Proceeds,  net of expenses,  received in respect of any
REO Property  (including,  without  limitation,  proceeds from the rental of the
related Mortgaged Property).
          REPLACEMENT MORTGAGE LOAN: A Mortgage Loan substituted by the Servicer
or  Seller  for a  Deleted  Mortgage  Loan  which  must,  on the  date  of  such
substitution, as confirmed in an Officers' Certificate delivered to the Trustee,
(i) have an  outstanding  Principal  Balance,  after  deduction of the principal
portion of the Monthly Payment due in the month of substitution  (or in the case
of a substitution of more than one Mortgage Loan for a Deleted Mortgage Loan, an
aggregate  Principal  Balance,  after  such  deduction),  not in  excess  of the
Principal Balance of the Deleted Mortgage Loan (the amount of any shortage to be
deposited by the Seller in the Certificate  Account in the month of substitution
as  set  forth  in  Section  2.04  of  this  Agreement);  (ii)  at the  time  of
substitution  have a Net Mortgage  Rate equal to or  exceeding  the Net Mortgage
Rate of the Deleted  Mortgage Loan;  (iii) have a Loan-to-Value  Ratio no higher
than the Loan-to-Value Ratio of the Deleted Mortgage Loan; (iv) have a remaining
term to  maturity  no  greater  than (and not more than one year less  than) the
Deleted   Mortgage   Loan;   (v)  be  of  the  same  or  better  credit  quality
classification  as that of the Deleted  Mortgage Loan; and (vi) comply with each
representation  and warranty relating to the Mortgage Loans set forth in Section
2.04 hereof.
          REQUIRED  INSURANCE  POLICY:  With respect to any Mortgage  Loan,  any
insurance  policy that is required to be maintained from time to time under this
Agreement in respect of such Mortgage Loan,  including each standard hazard and,
if applicable, flood insurance policy.
                                      -29-
          RESPONSIBLE  OFFICER:  When  used with  respect  to the  Trustee,  the
Chairman or Vice Chairman of the Board of Directors or Trustees, the Chairman or
Vice Chairman of the  Executive or Standing  Committee of the Board of Directors
or Trustees, the President,  the Chairman of the Committee on Trust Matters, any
Vice  President,  any Assistant Vice  President,  the  Secretary,  any Assistant
Secretary,  the Treasurer,  any Assistant Treasurer,  the Cashier, any Assistant
Cashier,  any Trust Officer or Assistant  Trust Officer,  the Controller and any
Assistant Controller or any other officer of the Trustee customarily  performing
functions similar to those performed by any of the above designated officers and
also, with respect to a particular matter, any other officer to whom such matter
is referred  because of such  officer's  knowledge of and  familiarity  with the
particular subject.
          S&P:  Standard & Poor's Ratings Agency,  a division of The ▇▇▇▇▇▇-▇▇▇▇
Companies, Inc.
          SCHEDULED  FINAL  DISTRIBUTION  DATE:  With  respect  to each Class of
Certificates,  other  than the Class AR5  Certificates,  the  Distribution  Date
occurring  in November  2039.  With respect to the Class AR5  Certificates,  the
Distribution Date occurring in November 2039.
          SELLER: Washington Mutual Bank, FA or its successor in interest.
          SENIOR  ACCELERATED  PREPAYMENT   PERCENTAGE:   With  respect  to  any
Distribution  Date and the  Class AR5  Certificates,  the  percentage  indicated
below:
          DISTRIBUTION DATE                   SENIOR ACCELERATED
                                           DISTRIBUTION PERCENTAGE
-------------------------------    --------------------------------------------
December 2001 through              100% (except as provided below)
November 2008.................
December 2008 through              Senior Percentage, plus 70% of the applicable
November 2009.................     Subordinate Percentage
December 2009 through              Senior Percentage, plus 60% of the applicable
November 2010.................     Subordinate Percentage
December 2010 through              Senior Percentage, plus 40% of the applicable
November 2011.................     Subordinate Percentage
December 2011 through              Senior Percentage, plus 20% of the applicable
November 2012.................     Subordinate Percentage
December 2012 and                  Senior  Percentage
thereafter.............................
          PROVIDED,  HOWEVER,  (i) if on or  prior to the  Distribution  Date in
November 2004, the Subordinate  Percentage for such Distribution Date is greater
than or equal to twice the  Subordinate  Percentage as of the Class AR5 Delivery
Date, then the Senior  Accelerated  Prepayment  Percentage for such Distribution
Date will equal the  Senior  Percentage  plus 50% the excess  over 100% over the
Senior  Percentage for such Distribution Date and (ii) for any Distribution Date
after
                                      -30-
November 2004, the Subordinate  Percentage for such Distribution Date is greater
than or equal to twice the  Subordinate  Percentage as of the Class AR5 Delivery
Date, then the Senior  Accelerated  Prepayment  Percentage for such Distribution
Date  will  equal the  Senior  Percentage,  PROVIDED,  FURTHER,  (i) the  Senior
Accelerated  Prepayment  Percentage will equal 100% on any Distribution  Date if
(1) the outstanding  principal balance of Class AR5 Mortgage Loans delinquent 60
days or more averaged over the last six months, as a percentage of the aggregate
Certificate   Principal  Balances  of  the  Class  B  Certificates  as  of  such
Distribution Date, is equal to or greater than 50% or (2) Realized Losses on the
Class AR5  Mortgage  Loans from the Class AR5 Cut-off  Date to date  exceed,  if
occurring during the eighth, ninth, tenth, eleventh or twelfth year (or any year
thereafter)  after the Class AR5  Delivery  Date,  30%,  35%,  40%,  45% or 50%,
respectively, of aggregate Initial Certificate Principal Balances of the Class B
Certificates  and  (ii)  that for any  Distribution  Date on  which  the  Senior
Percentage  is greater than the Senior  Percentage  as of the Class AR5 Delivery
Date, the Senior  Accelerated  Prepayment  Percentage for the Class AR5 Mortgage
Loans for such Distribution Date shall be 100%.  Notwithstanding  the foregoing,
upon the  reduction  of the  Certificate  Principal  Balances  of the  Class I-A
Certificates  to  zero,  the  Senior  Accelerated  Prepayment  Percentage  shall
thereafter be 0%.
          SENIOR  PERCENTAGE:  With  respect to any date of  determination,  the
aggregate of the Certificate  Principal  Balances of the Class I-A and Class I-R
Certificates,  divided  by the  aggregate  Principal  Balances  of the  Class AR
Mortgage Loans.
          SENIOR PRINCIPAL  DISTRIBUTION  AMOUNT: On each Distribution  Date, an
amount equal to the sum of the following:
               (a) the Senior  Percentage for such  Distribution  Date times the
     sum of the following:
                              (A) the principal  portion of each Monthly Payment
                    due  during  the  related  Due  Period  on each  Outstanding
                    Mortgage Loan that is a Class AR5 Mortgage Loan,  whether or
                    not received on or prior to the related  Determination Date;
                    and
                              (B) the  Principal  Balance of any  Mortgage  Loan
                    that is a Class AR5  Mortgage  Loan  repurchased  during the
                    related  Prepayment  Period pursuant to Section 2.01,  2.02,
                    2.03, 2.04 or 3.12 and the amount of any shortfall deposited
                    in the Custodial Account in connection with the substitution
                    of a Deleted Mortgage Loan that is a Class AR5 Mortgage Loan
                    pursuant to Section 2.01,  2.02,  2.03,  2.04 or 3.12 during
                    the related  Prepayment Period; and the principal portion of
                    all other  unscheduled  collections  (other  than  Principal
                    Prepayments in Full and Curtailments and amounts received in
                    connection  with a Cash  Liquidation or REO Disposition of a
                    Mortgage Loan that is a Class AR5 Mortgage Loan described in
                    clause (b) below,  including  without  limitation  Insurance
                    Proceeds,  Liquidation  Proceeds and REO Proceeds)  received
                    during the related  Prepayment  Period to the extent applied
                    by the  Servicer as  recoveries  of principal of the related
                    Mortgage  Loan that is a Class AR5 Mortgage Loan pursuant to
                    Section 3.13; and
                                      -31-
               (b)  with  respect  to each  Mortgage  Loan  that is a Class  AR5
     Mortgage Loan for which a Cash  Liquidation or a REO  Disposition  occurred
     during the related  Prepayment Period, an amount equal to the lesser of (a)
     the  applicable  Senior  Percentage  for such  Distribution  Date times the
     Principal  Balance of such Class AR5 Mortgage  Loan and (b) the  applicable
     Senior Accelerated Prepayment Percentage for such Distribution Date and the
     Class  AR5  Mortgage  Loans  times  the  related  unscheduled   collections
     (including without limitation Insurance Proceeds,  Liquidation Proceeds and
     REO  Proceeds)  to the extent  applied by the  Servicer  as  recoveries  of
     principal of the related Mortgage Loan pursuant to Section 3.13; and
               (c) the applicable Senior Accelerated  Prepayment  Percentage for
     such Distribution Date times the aggregate of all Principal  Prepayments in
     Full and  Curtailments  received in respect of the Class AR5 Mortgage Loans
     during the related Prepayment Period; and
               (d) any amounts  described in clause (a),  (b) and (c) above,  as
     determined for any previous  Distribution  Date,  which remain unpaid after
     application of amounts previously  distributed  pursuant to this clause (d)
     to the extent that such  amounts are not  attributable  to Realized  Losses
     which have been allocated to the Class B Certificates.
          SERVICER:  Washington Mutual Bank, FA or any successor under the terms
of this Agreement.
          SERVICER  ADVANCE DATE:  The date on which the Servicer is required to
make a Monthly Advance pursuant to Section 5.04 hereof.
          SERVICER  MORTGAGE FILE:  All documents  pertaining to a Mortgage Loan
not  required  to be  included  in the  Trustee  Mortgage  File  and held by the
Servicer or any Sub-Servicer.
          SERVICING FEE: For each calendar  month, as to each Mortgage Loan, (i)
an amount  equal to one  month's  interest  (or in the event of any  payment  of
interest  which  accompanies a Principal  Prepayment  in Full,  interest for the
number of days  covered  by such  payment  of  interest)  at a rate equal to the
Servicing Fee Rate and (ii)  increased by any late payment  charges,  assumption
fees and other usual and customary  fees collected from the Mortgagor and by any
net income on Eligible Investments held in the Custodial Account.
          SERVICING   FEE  RATE:   0.375%  per  annum   with   respect  to  each
adjustable-rate  Mortgage  Loan  and  0.250%  per  annum  with  respect  to each
fixed-rate Mortgage Loan.
          SERVICING  OFFICER:  Any  officer  of the  Servicer  involved  in,  or
responsible  for, the  administration  and servicing of the Mortgage Loans whose
name  appears on a list of  servicing  officers  furnished to the Trustee on the
Delivery Date by the Servicer pursuant to this Agreement,  as such list may from
time to time be amended.
          SPECIAL  HAZARD  COVERAGE:  The  Special  Hazard  Coverage on the most
recent  anniversary of the Class AR5 Cut-off Date (calculated in accordance with
the  second  sentence  of this  definition)  or,  if  prior  to the  first  such
anniversary,  $22,624,479,  in  each  case  reduced  by  Special  Hazard  Losses
allocated to the Class AR5 Certificates since the most recent anniversary of the
Class AR5 Cut-off  Date (or, if prior to the first such  anniversary,  since the
Class AR5 Cut-off Date). On each  anniversary of the Class AR5 Cut-off Date, the
Special Hazard Coverage shall be reduced, but not increased,  to an amount equal
to the lesser of (1) the greatest of (a) the aggregate principal
                                      -32-
balance of the Mortgage  Loans  located in the single  California  zip code area
containing the largest  aggregate  principal balance of Mortgage Loans, (b) 1.0%
of the aggregate  unpaid  principal  balance of the Mortgage Loans and (c) twice
the unpaid  principal  balance of the largest single Mortgage Loan, in each case
calculated  as of the  Due  Date in the  immediately  preceding  month,  and (2)
$22,624,479 as reduced by the Special  Hazard Losses  allocated to the Class AR5
Certificates since the Class AR5 Cut-off Date.
          The Special Hazard  Coverage may be reduced upon written  confirmation
from the Rating Agencies that such reduction will not adversely  affect the then
current ratings assigned to the Certificates by the Rating Agencies.
          SPECIAL HAZARD LOSS: A Realized Loss incurred,  to the extent that the
loss was  attributable  to (i) direct  physical  damage to a Mortgaged  Property
other than any loss of a type  covered by a hazard  insurance  policy or a flood
insurance  policy, if applicable,  and (ii) any shortfall in insurance  proceeds
for partial damage due to the application of the co-insurance  clauses contained
in hazard insurance  policies.  The amount of the Special Hazard Loss is limited
to the lesser of the cost of repair or  replacement  of the mortgaged  property.
Special  Hazard  Losses  do  not  include   losses   occasioned  by  war,  civil
insurrection, certain governmental actions, errors in design, faulty workmanship
or materials (except under certain  circumstances),  nuclear reaction,  chemical
contamination or waste by the Mortgagor.
          SUB-SERVICER: Any other entity with respect to any Mortgage Loan under
any Sub-Servicing  Agreement,  either currently or in the future,  applicable to
such  Mortgage  Loan and any  successors  and assigns  under such  Sub-Servicing
Agreement.
          SUB-SERVICING  AGREEMENT: Any servicing agreement between the Servicer
and a Sub-Servicer pursuant to which the Servicer delegates any of its servicing
responsibilities with respect to any of the Mortgage Loans.
          SUBCLASS:  With  respect  to the Class Y  Certificates,  any  Subclass
thereof issued  pursuant to Section  6.01(b) will  represent the  uncertificated
Class Y Mortgage Loans REMIC regular interest or interests relating to the Class
Y Mortgage  Loans  specified by the initial  Holder of the Class Y  Certificates
pursuant to Section 6.01(b).
          SUBORDINATE PRINCIPAL  DISTRIBUTION AMOUNT: On each Distribution Date,
an amount equal to the sum of:
          (a) the product of :
               (1) the  applicable  Class B Percentage  for the related Class of
Class B Certificates; and
               (2) the amounts calculated pursuant to clauses (a) and (b) of the
definition  of  "Senior  Principal   Distribution   Amount  to  the  extent  not
distributed to the Holders of the Senior  Certificates  pursuant to section 4.02
(a)(z)(ii),
                                      -33-
          (b) the product of :
               (1)  the  related  Prepayment  Distribution  Percentage  for  the
related Class of Class B Certificates; and
               (2) the amount of Principal  Prepayments in Full and Curtailments
received  in  respect  of the  Class  AR5  Mortgage  Loans  during  the  related
Prepayment Period and not distributed to the Holders of the Senior  Certificates
pursuant to Section 4.02(a)(z)(ii), and
          (c) amounts described clauses (a) and (b) above, as determined for any
previous  Distribution  Date, that remain  undistributed to the extent that such
amounts are not  attributable to Realized Losses on the related Class of Class B
Certificates.
          TRANSFEREE   AFFIDAVIT   AND   AGREEMENT:   As   defined   in  Section
6.02(g)(i)(B).
          TRUST  FUND:  Collectively,  the  assets  of the  Trust  REMIC and all
amounts deposited therein pursuant to the provisions of this Agreement.
          TRUST REMIC:  The corpus of the Trust Fund  created by this  Agreement
consisting  of (a) the  Mortgage  Loans listed in the  Mortgage  Loan  Schedule,
including all interest and principal  received or receivable by the Depositor on
or with respect to the Mortgage  Loans after the Cut-off Date, but not including
payments of principal  and interest due and payable on the Mortgage  Loans on or
before the  Cut-off  Date,  together  with the  Mortgage  Files  relating to the
Mortgage Loans, (b) REO Property,  (c) the Custodial Account and the Certificate
Account and all amounts deposited therein pursuant to the applicable  provisions
of this  Agreement,  (d) any  insurance  policies  with  respect to the Mortgage
Loans, (e) all proceeds of the conversion,  voluntary or involuntary,  of any of
the  foregoing  into cash or other liquid  property and (f) its rights under the
Mortgage Loan Purchase Agreement.
          TRUSTEE:   Bank  One,   National   Association,   a  national  banking
association,  not in its  individual  capacity,  but solely in its  capacity  as
trustee for the benefit of the Certificateholders  under this Agreement, and any
successor thereto, as provided herein.
          TRUSTEE FLOAT:  With respect to each  Distribution  Date, the value of
balances on deposit in the Certificate  Account (which shall not be invested) to
be held by the Trustee for the period  beginning  one Business Day prior to such
Distribution Date and ending on such Distribution Date.
          TRUSTEE  MORTGAGE  FILE:  The  mortgage  documents  listed in  Section
2.01(i)-(v)  hereof pertaining to a particular  Mortgage Loan and any additional
documents  required to be added to the Trustee  Mortgage  File  pursuant to this
Agreement.
          UNITED STATES  REGULATIONS:  31 C.F.R.  Part 357; 12 C.F.R.  Part 615,
Subpart O; 12 C.F.R. Part 912; 12 C.F.R. Part 1511; 24 C.F.R. Part 81; 31 C.F.R.
Part 354; and 18 C.F.R. Part 1314.
          UNITED STATES  SECURITIES  ENTITLEMENT:  A "Security  Entitlement"  as
defined in a United States Regulation.
                                      -34-
          U.S.   PERSON:   A  citizen  or  resident  of  the  United  States,  a
corporation,  partnership  or other entity created or organized in, or under the
laws of, the United  States or any state  (including  the  District of Columbia)
thereof,  or an estate or trust  whose  income from  sources  without the United
States is  includable  in gross  income for  United  States  federal  income tax
purposes  regardless of its  connection  with the conduct of a trade or business
within the United States.
          VOTING RIGHTS:  The portion of the aggregate  voting rights of all the
Certificates  evidenced  by a  Certificate.  99% of all  Voting  Rights  will be
allocated  to  the  Certificates  (other  than  the  Class  R  Certificates)  in
proportion  to their  Certificate  Principal  Balances  and 1.00% of all  Voting
Rights  will be  allocated  to the  Class R  Certificates.  Notwithstanding  the
foregoing, for so long as the Class AR5 Certificates are Outstanding, 99% of the
Voting Rights of the Class A-1, Class A-2, Class A-3 and Class A-4  Certificates
shall be  allocated  to the Class  AR5  Certificates  (other  than the Class I-R
Certificates) in proportion to their Certificate Principal Balances and 1.00% of
such Voting Rights will be allocated to the Class I-R Certificates.
          WASHINGTON MUTUAL: Washington Mutual Bank, FA.
                                   ARTICLE II
                            CONVEYANCE OF TRUST FUND;
                         REPRESENTATIONS AND WARRANTIES
     SECTION 2.01 CONVEYANCE OF TRUST FUND.
          As of Delivery Date, the Depositor hereby sells,  transfers,  assigns,
delivers,  sets over and otherwise conveys to the Trustee for the benefit of the
Certificateholders,  without recourse, the Depositor's right, title and interest
in and to the Trust REMIC,  and as of the Class AR5 Delivery Date, the Depositor
hereby sells, transfers,  assigns,  delivers, sets over and otherwise conveys to
the Trustee for the benefit of the  Certificateholders,  without  recourse,  the
Depositor's right, title and interest in and to the REMIC I and REMIC II.
          As of the Delivery Date, the Seller hereby sells, transfers,  assigns,
delivers, sets over and otherwise conveys to the Trustee,  without recourse, any
and all right,  title and  interest of the  Seller,  if any, in and to the Trust
REMIC and as of the Class AR5 Delivery Date, the Seller hereby sells, transfers,
assigns,  delivers,  sets over and  otherwise  conveys to the  Trustee,  without
recourse, any and all right, title and interest of the Seller, if any, in and to
the REMIC I and REMIC II and in the Class A-1, A-2, A-3 and A-4 Certificates.
          In connection with any such transfer and  assignment,  the Seller does
hereby  deliver to, and deposit with,  the Trustee or its agents,  the following
documents or instruments with respect to each Mortgage Loan so assigned:
               (i) the Mortgage Note, endorsed, in blank (which such endorsement
may be  pursuant  to the use of an allonge in the form  attached  as Exhibit J),
with all intervening  endorsements  showing a complete chain of endorsement from
the originator to the last endorser (or an original lost note affidavit from the
Seller  stating that the Mortgage Note was lost,  misplaced or  destroyed,  with
respect  to  such  Mortgage  Loans  identified  in the  Trustee's  Certification
referenced in Section  2.02),  and if the Mortgage Note or Mortgage or any other
material document or
                                      -35-
instrument  relating  to the  Mortgage  Loan has been  signed  on  behalf of the
Mortgagor by another person,  the original power of attorney or other instrument
that  authorized  and  empowered  such person to sign, or a copy of the original
power of attorney or other instrument;
               (ii)  the  original  Mortgage,  as  recorded,  with  evidence  of
recording indicated thereon establishing the Seller as mortgagee thereof;
               (iii) an original  assignment or assignments  of Mortgage  (other
than an  Assignment)  showing an unbroken  chain of title from the originator to
the Seller with evidence of recording  indicated thereon or a duplicate original
of the copy thereof certified by the applicable recording office;
               (iv) the original copy of each assumption,  modification, written
assurance or substitution agreement, if any, with respect to such Mortgage Loan,
as identified on the Mortgage Loan Schedule; and
               (v) an Assignment.
          Notwithstanding  the foregoing,  in the event that in connection  with
any Mortgage Loan the Seller cannot deliver an original recorded  counterpart of
any of the documents  required to be delivered pursuant to clauses (ii) or (iii)
above with  evidence of recording  thereon  concurrently  with the execution and
delivery hereof, the Seller shall deliver to the Trustee a duplicate original or
true copy of such  document  certified  by the Seller or the  applicable  public
recording  office to be a true and  complete  duplicate  original or copy of the
original thereof submitted for recording, or a copy of the Mortgage certified by
a title insurance or escrow company or companies,  evidencing that such Mortgage
or assignment of Mortgage has been delivered to the appropriate public recording
office for recordation.  In the event that the Seller cannot deliver a duplicate
original or true copy certified as stated above of such document  required to be
delivered  pursuant  to  clauses  (ii) or  (iii)  above,  within  45 days of the
Delivery  Date,  the Seller  shall  purchase  the related  Mortgage  Loan at the
Purchase  Price  therefor  or,  replace  the  Mortgage  Loan with a  Replacement
Mortgage  Loan  if  such  substitution   occurs  within  the  time  periods  for
substitution set forth in Section 2.04.
          The Seller  shall  promptly  deliver to the Trustee  (A) the  original
recorded  documents referred to in clauses (ii) and (iii) above with evidence of
recording  indicated thereon or a photocopy thereof certified by the appropriate
county recorder's office to be a true and complete copy of the original thereof,
upon receipt thereof from the public recording office, and (B) upon discovery of
any defect or omission in the deliveries of any of items (ii) through (iv) above
with respect to any Mortgage Loan, a correct and complete document or instrument
meeting the  requirements  of such item, but in no event shall any such delivery
be made later than 90 days  following the Delivery Date (unless,  in the case of
the foregoing  clause (A), such document has not been returned from the relevant
recording  office at such  time,  in which  case the  Servicer  shall  make such
delivery within 270 days of the Delivery Date; PROVIDED,  HOWEVER, that such 270
day period  shall be  extended  to 360 days upon  presentation  of an  officer's
certificate  of the Seller to the  effect  that such  document  has not yet been
returned  from  the  relevant  recording  office,  and  shall  be  extended  for
additional  thirty-day  periods).  In the event the Seller  cannot  deliver such
original  document  within the time period set forth in the preceding  sentence,
the Seller  shall  purchase  the related  Mortgage  Loan at the  Purchase  Price
therefor or, replace the Mortgage Loan with a Replacement  Mortgage Loan if such
substitution  occurs  within  the time  periods  for  substitution  set forth in
Section 2.04.
                                      -36-
          From time to time the Seller or the  Servicer  may forward or cause to
be forwarded to the Trustee for the benefit of the Certificateholders additional
original documents evidencing an assumption or modification of a Mortgage Loan.
          The Seller will  promptly  notify,  in  writing,  the  Depositor,  the
Servicer and the Trustee of the occurrence of a Downgrade Event.
          Within 60 days  following  the  receipt of the  notice of a  Downgrade
Event, the Trustee shall (a) complete each endorsement referred to in clause (i)
above and each Assignment  referred to in (v) above by inserting "to the Trustee
for the benefit of the Holders of the Washington Mutual Bank, FA Mortgage-Backed
Pass-Through Certificates, Series 1999-WM4" and (b) cause the Servicer to record
(and the Servicer hereby agrees to record),  at the expense of the Servicer,  in
the appropriate public office for real property records each original assignment
referred  to in (v) above  with  respect  to each  Mortgaged  Property,  and the
Trustee shall release any such Assignment to the Servicer for such purpose.  The
Servicer shall  promptly  deliver to the Trustee each original  Assignment  with
evidence of recording  indicated thereon or a photocopy thereof certified by the
appropriate  county  recorder's  office  to be a true and  complete  copy of the
original thereof,  upon receipt thereof from the public recording  official.  If
any  Assignment  is returned  unrecorded  to the Servicer  because of any defect
therein,  the Seller or the Servicer shall cure or correct such defect and cause
such  Assignment  to be recorded in accordance  with this  paragraph and if such
defect is not cured within 60 days the Seller shall  purchase the Mortgage  Loan
at the Purchase  Price therefor or, replace the Mortgage Loan with a Replacement
Mortgage  Loan  if  such  substitution   occurs  within  the  time  periods  for
substitution set forth in Section 2.04.
     SECTION 2.02 ACCEPTANCE BY TRUSTEE.
          The Trustee will hold the documents referred to in Section 2.01(i)-(v)
above and the other documents  constituting a part of the Trustee Mortgage Files
delivered to it pursuant to Section 2.01 in trust for the use and benefit of all
present  and future  Certificateholders.  Upon  execution  and  delivery of this
Agreement and within 45 days after the execution and delivery of this Agreement,
the Trustee shall ascertain whether all documents required to be delivered to it
pursuant to Section 2.01 hereof are in its possession,  and shall deliver to the
Depositor,  the Seller and the  Servicer a  certification  (upon  execution  and
delivery  of this  Agreement,  the  "Initial  Certification"  and within 45 days
thereof,  the  "Final  Certification,"  respectively)  in the forms set forth as
EXHIBITS D-1 and D-2 hereto to the effect that,  as to each Mortgage Loan listed
in the Mortgage Loan Schedule: (a) all documents required to be delivered to the
Trustee  pursuant to this  Agreement are in its  possession,  (b) such documents
have been reviewed by it and have not been mutilated,  damaged, defaced, torn or
otherwise  physically  altered,  and such documents relate to such Mortgage Loan
and (c) each Mortgage Note has been endorsed and each assignment of Mortgage has
been delivered as provided in Section 2.01 hereof.  The Trustee shall deliver to
the Depositor,  the Seller and the Servicer a copy of such Final  Certification.
If, in the course of such  review,  the Trustee  finds any document or documents
constituting a part of a Mortgage File which do not meet the requirements of the
foregoing  clauses  (a)-(c),  the Trustee shall promptly notify the Seller,  the
Servicer and the  Depositor in writing,  and request that the Seller  correct or
cure such defect.  The Trustee shall promptly  notify the Depositor,  the Seller
and the  Servicer in writing if any  original  assignment  referred to in clause
(iii) of Section 2.01 or duplicate original or the copy thereof certified by the
Seller or the applicable  recording  office has not been received by it prior to
March  31,  2000.  In the  event  the  Seller  shall  fail to cure any  document
deficiency or defect reflected in the Final
                                      -37-
Certification or as otherwise required under Section 2.01 within 60 days of such
Final Certification,  it shall not be the obligation of the Trustee hereunder to
cure the same,  and the Seller shall  purchase the Mortgage Loan at the Purchase
Price  therefor or, if within ninety days or two years of the Delivery  Date, as
applicable,  substitute  the Mortgage Loan with a  Replacement  Mortgage Loan in
accordance with the provisions of Sections 2.04.
          The  Depositor  agrees  that at any time and  from  time to time  upon
written  request of the Trustee,  the Depositor  shall promptly and duly execute
and deliver any and all such further  documents  and  assurances,  and take such
further actions as the Trustee reasonably may request in order to obtain or more
fully vest the  benefits  of the  assignment  intended  hereunder  (as set forth
hereinabove  in Section 2.01 and  hereinbelow in Section 2.03) and of the rights
and powers herein granted.
          The  Trustee  shall  retain  possession  and  custody  of the  Trustee
Mortgage File in  accordance  with and subject to the terms and  conditions  set
forth herein.
     SECTION 2.03 REPRESENTATIONS,  WARRANTIES AND COVENANTS OF THE SERVICER AND
SELLER.
          Washington  Mutual,  as Seller and  Servicer,  hereby  represents  and
warrants to, and covenants  with,  the Depositor and the Trustee that, as of the
Delivery Date and as of the Class AR5 Delivery Date:
               (i)   Washington   Mutual  is  a  federally   chartered   savings
association,  validly existing and in good standing under the laws of the United
States of America and is duly  authorized  and qualified to transact any and all
business  contemplated  by this  Agreement  in any  state in  which a  Mortgaged
Property is located or is otherwise not required under  applicable law to effect
such  qualification  and, in any event, is in compliance with the doing business
laws of any such state, to the extent necessary to ensure the  enforceability of
each Mortgage Loan and the  servicing of the Mortgage  Loans in accordance  with
the terms of this Agreement;
               (ii) Washington Mutual has the full corporate power and authority
to service each Mortgage Loan, and to execute, deliver and perform, and to enter
into and consummate the transactions contemplated by this Agreement and has duly
authorized by all necessary  corporate  action on the part of Washington  Mutual
the execution,  delivery and performance of this Agreement;  and this Agreement,
assuming the due authorization,  execution and delivery thereof by the Depositor
and the Trustee, constitutes a legal, valid and binding obligation of Washington
Mutual,  enforceable  against  Washington  Mutual in accordance  with its terms,
except  that  (A) the  enforceability  thereof  may be  limited  to  bankruptcy,
insolvency,  moratorium,   receivership  and  other  similar  laws  relating  to
creditors'  rights  generally  and (B) the remedy of  specific  performance  and
injunctive  and other forms of equitable  relief may be subject to the equitable
defenses and to the discretion of the court before which any proceeding therefor
may be brought;
               (iii) the execution and delivery of this  Agreement by Washington
Mutual, the servicing of the Mortgage Loans by Washington Mutual hereunder,  the
consummation  of any  other of the  transactions  herein  contemplated,  and the
fulfillment of or compliance with the terms hereof are in the ordinary course of
business of  Washington  Mutual and will not (A) result in a material  breach of
any term or provision of the charter or by-laws of Washington Mutual or
                                      -38-
(B)  materially  conflict  with,  result  in a  material  breach,  violation  or
acceleration  of, or result in a material  default under, the terms of any other
material  agreement or  instrument to which  Washington  Mutual is a party or by
which it may be  bound,  or any  statute,  order  or  regulation  applicable  to
Washington  Mutual  of any  court,  regulatory  body,  administrative  agency or
governmental  body having  jurisdiction over Washington  Mutual;  and Washington
Mutual is not a party to,  bound by, or in breach or  violation  of any material
indenture  or other  material  agreement  or  instrument,  or  subject  to or in
violation of any statute,  order or  regulation of any court,  regulatory  body,
administrative  agency or governmental  body having  jurisdiction over it, which
materially  and  adversely  affects,  (1) the  ability of  Washington  Mutual to
perform its  obligations  under this Agreement or (2) the business,  operations,
financial condition, properties or assets of the Servicer taken as a whole;
               (iv)   Washington   Mutual  is,  and  will  remain,   subject  to
supervision  and  examination  by  any  state  or  federal  authority  as may be
applicable  and will remain in good standing and qualified to do business  where
so required by  applicable  law and is, and will remain an approved  servicer of
conventional mortgage loans for ▇▇▇▇▇▇ ▇▇▇ or Freddie Mac;
               (v) no  litigation is pending or  threatened  against  Washington
Mutual that would  materially and adversely  affect the  execution,  delivery or
enforceability  of this Agreement or the ability of Washington Mutual to service
the  Mortgage  Loans or to perform  any of its other  obligations  hereunder  in
accordance with the terms hereof;
               (vi)   Washington   Mutual  will  at  all  times  comply  in  the
performance of its  obligations  under this Agreement with all reasonable  rules
and requirements of the insurer under each Required Insurance Policy;
               (vii)  no  written   information,   certificate  of  an  officer,
statement furnished in writing or written report delivered to the Depositor, any
affiliate  of the  Depositor or the Trustee and  prepared by  Washington  Mutual
pursuant to this Agreement will contain any untrue  statement of a material fact
or omit to state a material fact necessary to make the information, certificate,
statement or report not misleading;
               (viii)  except for permits and  similar  authorizations  required
under the securities or "blue sky" laws no consent,  approval,  authorization or
order of any court or governmental agency or body is required for the execution,
delivery and  performance  by Washington  Mutual of, or compliance by Washington
Mutual with, this Agreement or the consummation of the transactions contemplated
hereby,  or if any such consent,  approval,  authorization or order is required,
Washington Mutual has obtained the same;
               (ix)  Washington  Mutual  will  service  the  Mortgage  Loans  in
accordance with the standards set forth in this Agreement; and
               (x) this  Agreement  and all other  documents  related  hereto to
which Washington Mutual is a party have been approved by the Washington Mutual's
board of  directors,  which  approval is reflected in the minutes of such board,
and shall  continuously  from the time of each  such  document's  execution,  be
maintained as an official record of the Washington Mutual.
                                      -39-
     SECTION 2.04  REPRESENTATIONS,  WARRANTIES AND COVENANTS OF THE SELLER WITH
RESPECT TO THE MORTGAGE LOANS.
          The Seller hereby  represents and warrants to, and covenants with, the
Depositor and the Trustee for the benefit of the Certificateholders  that, as to
each  Mortgage  Loan,  as of the Cut-off Date and, with respect to the Class AR5
Mortgage Loans, the Class AR5 Delivery Date or such other date  specifically set
forth herein,
               (i) The  information  set forth in the Mortgage  Loan Schedule is
complete,  true and correct as of the Cut-off Date and the information set forth
on the  Schedule  X with  respect  to the Class AR5  Mortgage  Loans is true and
correct as of the Class AR5 Cut-off Date.
               (ii) As of the Cut-off Date, none of the Mortgage Loans were more
than 30 days  delinquent  and not more than 0.71% of the Mortgage  Loans were 30
days  delinquent  more than once in the twelve months prior to the Cut-off Date;
and as of the Class AR5  Cut-off  Date,  none of the  Mortgage  Loans  listed on
Schedule  X were more  than 30 days  delinquent  and not more than  6.43% of the
Mortgage Loans listed on Schedule X were 30 days or more  delinquent one or more
times in the  twelve  months  prior to the Class AR5  Cut-off  Date;  Washington
Mutual has not advanced  funds to, or induced,  solicited or knowingly  received
any advance of funds from a party other than the owner of the Mortgaged Property
subject to the Mortgage,  directly or indirectly,  for the payment of any amount
required by the Mortgage Loan.
               (iii) There are no delinquent taxes, ground rents, water charges,
sewer rents,  assessments,  insurance premiums,  leasehold  payments,  including
assessments   payable  in  future  installments  or  other  outstanding  charges
affecting the related Mortgaged Property.
               (iv) The terms of the  Mortgage  Note and the  Mortgage  have not
been  impaired,  waived,  altered or modified in any respect,  except by written
instruments  which have been recorded,  if necessary to protect the interests of
the Trustee,  and which are included in the Trustee Mortgage File, the substance
of which  waiver,  alteration or  modification  has been approved by the primary
mortgage  guaranty  insurer,  if any,  and by the title  insurer,  to the extent
required by the related  policy and is reflected on the Mortgage Loan  Schedule.
No instrument of waiver,  alteration or modification  has been executed,  and no
Mortgagor has been released,  in whole or in part,  except in connection with an
assumption agreement approved by the primary mortgage insurer, if any, and title
insurer, to the extent required by the policy, and which assumption agreement is
part of the Mortgage File.
               (v) The  Mortgage  Note and the  Mortgage  are not subject to any
right of rescission,  set-off, counterclaim or defense, including the defense of
usury,  nor will the  operation  of any of the  terms of the  Mortgage  Note and
Mortgage,  or  the  exercise  of  any  right  thereunder,  render  the  Mortgage
unenforceable,  in whole or in part,  or  subject  to any  right of  rescission,
set-off,  counterclaim  or defense,  including  the defense of usury and no such
right of  rescission,  set-off,  counterclaim  or defense has been asserted with
respect thereto.
               (vi) All buildings  upon the Mortgaged  Property are insured by a
generally  acceptable insurer against loss by fire, hazards of extended coverage
and such other hazards as are customary in the area where the Mortgaged Property
is located.  All such insurance  policies  contain a standard  mortgagee  clause
naming the Servicer, its successors and assigns as mortgagee and all
                                      -40-
premiums  thereon have been paid. If upon  origination of the Mortgage Loan, the
Mortgaged  Property  was in an area  identified  in the Federal  Register by the
Federal  Emergency  Management  Agency as having special flood hazards (and such
flood insurance has been made  available) a flood  insurance  policy meeting the
requirements of the current  guidelines of the Federal Insurance  Administration
is in effect which policy conforms to the  requirements of ▇▇▇▇▇▇ ▇▇▇ or Freddie
Mac.  The  Mortgage  obligates  the  Mortgagor  thereunder  to maintain all such
insurance at ▇▇▇▇▇▇▇▇▇'s cost and expense,  and on the Mortgagor's failure to do
so,  authorizes  the  holder of the  Mortgage  to  maintain  such  insurance  at
▇▇▇▇▇▇▇▇▇'s  cost  and  expense  and to seek  reimbursement  therefor  from  the
Mortgagor.
               (vii) Any and all requirements of any federal, state or local law
including,  without  limitation,  environmental,  usury, truth in lending,  real
estate  settlement   procedures,   consumer  credit  protection,   equal  credit
opportunity or disclosure  laws  applicable to the Mortgage Loan and the related
Mortgaged Property have been complied with.
               (viii)  The  Mortgage  has  not  been   satisfied,   canceled  or
subordinated,  or rescinded, in whole or in part, and the Mortgaged Property has
not been released from the lien of the  Mortgage,  in whole or in part,  nor has
any instrument  been executed that would effect any such release,  cancellation,
subordination or rescission.
               (ix) The Mortgage is a valid, existing and enforceable first lien
on the Mortgaged Property,  including all improvements on the Mortgaged Property
subject only to (A) the lien of current real property taxes and  assessments not
yet due and payable, (B) covenants, conditions and restrictions,  rights of way,
easements  and other  matters of the public  record as of the date of  recording
being  acceptable to mortgage  lending  institutions  generally and specifically
referred to in lender's title  insurance  policy  delivered to the originator of
the Mortgage Loan and which do not adversely  affect the Appraised  Value of the
Mortgaged Property,  and (C) other matters to which like properties are commonly
subject  which do not  materially  interfere  with the  benefits of the security
intended  to be  provided  by the  Mortgage  or the  use,  enjoyment,  value  or
marketability of the related Mortgaged Property. Any security agreement, chattel
mortgage or equivalent  document related to and delivered in connection with the
Mortgage  establishes and creates a valid,  existing and enforceable  first lien
and first priority security  interest on the property  described therein and the
Seller  has full  right  to sell  and  assign  the  same to the  Depositor.  The
Mortgaged  Property was not, as of the date of origination of the Mortgage Loan,
subject to a  mortgage,  deed of trust,  deed to secure  debt or other  security
instrument creating a lien subordinate to the lien of the Mortgage.
               (x) The  Mortgage  Note and the related  Mortgage are genuine and
each  is  the  legal,  valid  and  binding  obligation  of  the  maker  thereof,
enforceable in accordance with its terms,  except as the enforceability  thereof
may be limited by bankruptcy, insolvency, or reorganization.
               (xi) All parties to the Mortgage  Note and the Mortgage had legal
capacity to enter into the Mortgage Loan and to execute and deliver the Mortgage
Note and the Mortgage, and the Mortgage Note and the Mortgage have been duly and
properly executed by such parties.
               (xii) The proceeds of the Mortgage Loan have been fully disbursed
and there is no  requirement  for  future  advances  thereunder  and any and all
requirements  as to completion of any on-site or off-site  improvement and as to
disbursements  of any escrow funds  therefor have been complied with. All costs,
fees and expenses incurred in making or closing the
                                      -41-
Mortgage Loan and the recording of the Mortgage were paid,  and the Mortgagor is
not entitled to any refund of any amounts paid or due under the Mortgage Note or
Mortgage.
               (xiii)  As of the  Delivery  Date,  the  Mortgage  Note  and  the
Mortgage are not assigned or pledged,  and immediately  prior to the sale of the
Mortgage  Loan to the  Depositor  the  Seller  was the sole  owner of record and
holder thereof and with full right to transfer and sell the Mortgage Loan to the
Depositor free and clear of any encumbrance, equity, lien, pledge, charge, claim
or security interest and with full right and authority subject to no interest or
participation  of, or agreement  with, any other party,  to sell and assign each
Mortgage Loan pursuant to the Mortgage Loan Purchase Agreement.
               (xiv) All parties  which have had any  interest in the  Mortgage,
whether as mortgagee, assignee, pledgee or otherwise, are (or, during the period
in which they held and disposed of such interest,  were) (A) in compliance  with
any and all applicable  licensing  requirements of the laws of the state wherein
the Mortgaged  Property is located,  and (B) either (i) organized under the laws
of such state,  or (ii) qualified to do business in such state, or (iii) federal
savings and loan associations or national banks having principal offices in such
state, or (iv) not doing business in such state.
               (xv) The  Mortgage  Loan is  covered  by an ALTA  lender's  title
insurance  policy  acceptable  to ▇▇▇▇▇▇ ▇▇▇ or Freddie  Mac,  issued by a title
insurer  acceptable to ▇▇▇▇▇▇ ▇▇▇ or Freddie Mac and qualified to do business in
the jurisdiction where the Mortgaged  Property is located,  insuring (subject to
the  exceptions  contained  in  (ix)(A)  through  (C)  above)  the  Seller,  its
successors  and  assigns as to the first  priority  lien of the  Mortgage in the
original  principal amount of the Mortgage Loan. The original title policy (or a
copy thereof  sufficient to entitle the insured to make a claim  thereunder) and
all riders thereto are in the Mortgage File.  Additionally,  such lender's title
insurance  policy   affirmatively   insures  ingress  and  egress,  and  against
encroachments  by or upon the Mortgaged  Property or any interest  therein.  The
Seller is the sole insured of such lender's  title  insurance  policy,  and such
lender's title insurance  policy is in full force and effect and will be in full
force and effect upon the consummation of the transactions  contemplated by this
Agreement.  No claims have been made under such lender's title insurance policy,
and no prior holder of the related Mortgage,  including the Seller, has done, by
act or omission, anything which would impair the coverage of such lender's title
insurance policy.
               (xvi)  There  is  no  default,  breach,  violation  or  event  of
acceleration  existing  under the  Mortgage  or the  Mortgage  Note and no event
which,  with the passage of time or with notice and the  expiration of any grace
or cure  period,  would  constitute  a default,  breach,  violation  or event of
acceleration,  and the Seller has not waived any default,  breach,  violation or
event of acceleration.
               (xvii) There are no  mechanics'  or similar liens or claims which
have been filed for work,  labor or material (and no rights are outstanding that
under law could give rise to such lien) affecting the related Mortgaged Property
which are or may be liens prior to, or equal or on parity with,  the lien of the
related Mortgage.
               (xviii) All improvements which were considered in determining the
Appraised  Value  of the  related  Mortgaged  Property  lay  wholly  within  the
boundaries and building
                                      -42-
restriction  lines of the Mortgaged  Property,  and no improvements on adjoining
properties encroach upon the Mortgaged Property.
               (xix)  The  Mortgage  Loan  was  originated  by the  Seller  or a
subsidiary of the Seller or was purchased by the Seller from a third party, each
of which was, at the time of origination,  (A) a ▇▇▇▇▇▇  ▇▇▇-approved or Freddie
Mac-approved  seller/servicer  and  (B) a  HUD-approved  mortgage  banker,  or a
savings and loan  association,  a savings  bank,  a  commercial  bank or similar
banking  institution  which is  supervised  and  examined  by a federal or state
authority.  Principal payments on the Mortgage Loan commenced no more than sixty
days after funds were  disbursed  in  connection  with the  Mortgage  Loan.  The
Mortgage Note is payable on the first day of each month in monthly  installments
of principal  and  interest,  with  interest in arrears,  and  requires  Monthly
Payments  sufficient to amortize the original  principal balance of the Mortgage
Loan over a term of not more than 40 years.  Each  Mortgage  Note has a Mortgage
Rate,  other  than a Mortgage  Note with a fixed  Mortgage  Rate,  that after an
initial  one-year,  three-year or five-year  period is calculated based upon the
Index plus the Margin.  Each Mortgage Note that is not calculated based upon the
Index plus the Margin,  provides for a fixed Mortgage Rate. No Mortgage Loan has
a provision which will require negative amortization.  No Mortgage Loan requires
a balloon payment at the end of its term.
               (xx)  The  origination  practices  used  by the  Seller  and  the
collection practices used by the Servicer with respect to each Mortgage Note and
Mortgage have been in all respects legal,  proper,  prudent and customary in the
mortgage origination and servicing business. With respect to escrow deposits and
escrow  payments,  if any, all such payments are in the  possession of, or under
the  control of, the  Servicer  and there exist no  deficiencies  in  connection
therewith for which customary  arrangements for repayment  thereof have not been
made. No escrow deposits or escrow payments or other charges or payments due the
Seller have been capitalized under any Mortgage or the related Mortgage Note.
               (xxi) The  Mortgaged  Property  is free of  damage  and waste and
there is no proceeding pending for the total or partial condemnation thereof.
               (xxii) The Mortgage contains customary and enforceable provisions
such as to render the rights and remedies of the holder thereof adequate for the
realization  against  the  Mortgaged  Property of the  benefits of the  security
provided thereby,  including, (A) in the case of a Mortgage designated as a deed
of trust, by trustee's sale, and (B) otherwise by judicial foreclosure. There is
no other  exemption  available to the Mortgagor  which would  interfere with the
right  to sell  the  Mortgaged  Property  at a  trustee's  sale or the  right to
foreclose  the  Mortgage.  The  Mortgagor  has not notified the Servicer and the
Servicer has no knowledge  of any relief  requested or allowed to the  Mortgagor
under the Relief Act.
               (xxiii)  The  Mortgage   Loan  was   underwritten   generally  in
accordance  with the Seller's  underwriting  standards in effect at the time the
Mortgage Loan was originated.
               (xxiv) The Mortgage Note is not secured by any collateral  except
the  lien  of the  corresponding  Mortgage  and  the  security  interest  of any
applicable security agreement or chattel mortgage referred to in (ix) above.
                                      -43-
               (xxv) The  Mortgage  File  contains an  appraisal  of the related
Mortgaged Property signed prior to the approval of the Mortgage Loan application
by a qualified appraiser, duly appointed by the originator of the Mortgage Loan,
who had no interest, direct or indirect in the Mortgaged Property or in any loan
made on the  security  thereof,  and whose  compensation  is not affected by the
approval or disapproval of the Mortgage Loan.
               (xxvi) In the event the Mortgage  constitutes a deed of trust,  a
trustee, duly qualified under applicable law to serve as such, has been properly
designated and currently so serves and is named in the Mortgage,  and no fees or
expenses are or will become  payable by the  Depositor to the trustee  under the
deed of trust,  except, in connection with a trustee's sale after default by the
Mortgagor.
               (xxvii) No Mortgage  Loan contains  provisions  pursuant to which
Monthly  Payments  are (A) paid or  partially  paid with funds  deposited in any
separate account  established by the Seller, the Mortgagor,  or anyone on behalf
of the  Mortgagor,  (B)  paid by any  source  other  than the  Mortgagor  or (C)
contains  any  other  similar   provisions  which  may  constitute  a  "buydown"
provision. No Mortgage Loan was a graduated payment mortgage loan as of the date
of its  origination.  No  Mortgage  Loan  has a  shared  appreciation  or  other
contingent interest feature.
               (xxviii)  The Seller has no  knowledge  of any  circumstances  or
condition  existing  on the  Cut-off  Date with  respect  to the  Mortgage,  the
Mortgaged  Property,  the Mortgagor or the Mortgagor's  credit standing that can
reasonably  be  expected  to  cause  the  Mortgage  Loan  to be an  unacceptable
investment,  cause the Mortgage Loan to become  delinquent,  or adversely affect
the value of the Mortgage Loan.
               (xxix)  Each such  Mortgage  Loan with a  Loan-to-Value  Ratio at
origination  in  excess  of 80% is and will be  subject  either to (x) a Primary
Mortgage  Insurance  Policy,  issued by a ▇▇▇▇▇▇  ▇▇▇ or  Freddie  Mac  approved
insurer,  which provided private mortgage  insurance in an amount meeting ▇▇▇▇▇▇
▇▇▇ and  Freddie  Mac  requirements  or (y) a  higher  interest  rate in lieu of
obtaining  private mortgage  insurance.  All provisions of such Primary Mortgage
Insurance  Policy have been and are being complied with,  such policy is in full
force and effect,  and all premiums due thereunder  have been paid. Any Mortgage
subject to any such Primary  Mortgage  Insurance  Policy obligates the Mortgagor
thereunder  to maintain  such  insurance  and to pay all premiums and charges in
connection therewith.
               (xxx)  The  Mortgaged   Property  is  lawfully   occupied   under
applicable law. All inspections,  licenses and certificates  required to be made
or issued  with  respect  to all  occupied  portions  of the  related  Mortgaged
Property and,  with respect to the use and occupancy of the same,  including but
not limited to  certificates  of  occupancy,  had been made or obtained from the
appropriate authorities.
               (xxxi) No action has been  taken or failed to be taken,  no event
has  occurred  and no state of facts  exists or has  existed  on or prior to the
Cut-off Date (whether or not known to the Seller on or prior to such date) which
has resulted or will result in an exclusion from, denial of, or defense coverage
under  any  private  mortgage  insurance  (including,  without  limitation,  any
exclusions,  denials or defenses which would limit or reduce the availability of
the timely  payment of the full amount of the loss  otherwise due  thereunder to
the insured) whether arising out of actions, representations, errors, omissions,
negligence, or fraud of the Seller, the related Mortgagor or any
                                      -44-
party involved in the  application  for such coverage,  including the appraisal,
plans and specifications and other exhibits or documents  submitted therewith to
the insurer  under such  insurance  policy,  or for any other  reason under such
coverage, but not including the failure of such insurer to pay by reason of such
insurer's breach of such insurance policy or such insurer's  financial inability
to pay.
               (xxxii) The  Assignment is in  recordable  form and is acceptable
for recording under the laws of the jurisdiction in which the Mortgaged Property
is located.
               (xxxiii) Any advances made to the Mortgagor  prior to the Cut-off
Date have been consolidated with the outstanding principal amount secured by the
Mortgage,  and the secured  principal  amount,  as consolidated,  bears a single
interest rate and single  repayment term. The lien of the Mortgage  securing the
consolidated principal amount is expressly insured as having first lien priority
by a  title  insurance  policy,  an  endorsement  to  the  policy  insuring  the
mortgagee's  consolidated  interest or by other  title  evidence  acceptable  to
▇▇▇▇▇▇ ▇▇▇ or Freddie Mac. The consolidated principal amount does not exceed the
original principal amount of the Mortgage Loan.
               (xxxiv) If the  Mortgaged  Property  is a  condominium  unit or a
planned unit development (other than a de minimis planned unit development) such
condominium or planned unit development  project meets ▇▇▇▇▇▇ ▇▇▇ or ▇▇▇▇▇▇▇ Mac
eligibility requirements.
               (xxxv) Each  Mortgage is a "qualified  mortgage"  for purposes of
the REMIC Provisions.
               (xxxvi) No fraud was committed by the  originator of the Mortgage
Loan and the  Seller  is not aware of any fact that  would  reasonably  lead the
Seller to believe that any ▇▇▇▇▇▇▇▇▇ had committed  fraud in connection with the
origination of such Mortgage Loan.
               (xxxvii)  The Index on all of the all of the  Class AR5  Mortgage
Loans is either the One-Year MTA Index or the One-Year CMT Index.
          Upon the discovery by the Depositor,  the Seller,  the Servicer or the
Trustee (or upon notice thereof in writing from a Certificateholder) of a breach
or breaches of any of the  representations  and warranties of the Seller made in
this  Section  2.04  in  respect  of  any  Mortgage  Loan,  or any  breach  of a
representation  or warranty of the Seller or Servicer  set forth in Section 2.03
or any breach of  representation  or  warranty of the Seller in Section 2 of the
Mortgage Loan Purchase Agreement,  which breach or breaches,  individually or in
the   aggregate,   materially   and  adversely   affect  the  interests  of  the
Certificateholders,  the party discovering such breach shall give prompt written
notice to the other parties.  The Trustee shall  promptly  notify the Seller and
Servicer of such breach and request that the Seller or Servicer, as the case may
be, cure such  breach  within 60 days (or if such breach is not capable of being
cured within 60 days and provided the Seller or the Servicer, as the case may be
is diligently pursuing the cure thereof,  within 120 days) from the date of such
notice,  and if the Seller or Servicer does not cure such breach in all material
respects,  the  Seller  or  Servicer,  as the  case  may be,  shall  either  (i)
substitute a Replacement  Mortgage Loan or Loans for the related  Mortgage Loan,
which  substitution  must be made as specified in this Section or (ii)  purchase
such  Mortgage  Loan held for the  benefit  of the  Certificateholders  from the
Trustee at the Purchase Price therefor.
                                      -45-
          The  Seller  or  Servicer  shall not have any  right to  substitute  a
Replacement  Mortgage  Loan or Loans for the  affected  Mortgage  Loan more than
three months after the Delivery  Date (or more than two years after the Delivery
Date if the related Mortgage Loan is a "defective obligation" within the meaning
of  Section  860G(a)(4)(B)(ii)  of the  Code),  and  any  substitution  must  be
accompanied  by an Officers'  Certificate  delivered to the Trustee,  certifying
that  such  Replacement  Mortgage  Loan  conforms  to the  requirements  of this
Agreement,  and by an Opinion of  Counsel to the effect  that such  substitution
will not cause  the Trust  REMIC,  REMIC I or REMIC II to fail to  qualify  as a
REMIC and will not result in a  prohibited  transaction  tax,  which  Opinion of
Counsel  shall  be paid  for by the  Seller  or  Servicer,  as the  case may be.
Notwithstanding the foregoing, if any such breach would cause a Mortgage Loan to
be other than a "qualified  mortgage loan" as described in Section 860G(a)(3) of
the  Code,  any  substitution  or  purchase  shall  occur  within 90 days of the
discovery of the breach.
          As to any Replacement  Mortgage Loan or Loans,  the Seller or Servicer
shall deliver to the Trustee or its agent for such Replacement  Mortgage Loan or
Loans, the Mortgage Note, the Mortgage,  and such other documents and agreements
as are required by Section 2.01, with the Mortgage Note (i) endorsed in blank if
no  Downgrade  Event has  occurred  or (ii) if a Downgrade  Event has  occurred,
endorsed to the Trustee for the benefit of the Holders of the Washington  Mutual
Bank, FA Mortgage-Backed  Certificates,  Series 1999-WM4 (which endorsement,  in
either case, may be in the form of an allonge).  As to any Replacement  Mortgage
Loan or Loans,  the Seller or Servicer  shall deliver to the Trustee the related
Assignment  (i) in blank in  recordable  form or (ii) if a  Downgrade  Event has
occurred,  assigned  to the  Trustee  for  the  benefit  of the  Holders  of the
Washington Mutual Bank, FA  Mortgage-Backed  Certificates,  Series 1999-WM4.  No
substitution will be made in any calendar month after the Determination Date for
such month.  Monthly Payments due with respect to Replacement  Mortgage Loans in
the  month  of  substitution  shall  not be part of the  Trust  Fund and will be
remitted by the Servicer to the Seller on the next succeeding Distribution Date.
For the month of substitution,  distributions to Certificateholders will include
the  Monthly  Payment  due on such  Deleted  Mortgage  Loan for such  month  and
thereafter  the Seller or  Servicer,  as the case may be,  shall be  entitled to
retain all amounts received in respect of such Deleted Mortgage Loan.
          Upon  such  substitution,  the  Servicer  shall  amend  or cause to be
amended the  Mortgage  Loan  Schedule  to reflect  the  removal of such  Deleted
Mortgage Loan and the substitution of the Replacement Mortgage Loan or Loans and
shall deliver such amended  Mortgage Loan Schedule to the Depositor,  the Seller
and the Trustee. Upon such substitution,  the Replacement Mortgage Loan or Loans
shall be subject to the terms of this  Agreement  in all respects and the Seller
shall be deemed to have made,  as of the date of  substitution,  with respect to
the  Replacement  Mortgage Loan or Loans,  the  representations  and  warranties
pertaining to the Mortgage Loans contained in Section 2.04 hereof.  Upon receipt
of the Trustee  Mortgage File pertaining to any Replacement  Mortgage Loans, the
Trustee shall release,  or cause to be released,  the Trustee Mortgage File held
for the benefit of the Certificateholders relating to such Deleted Mortgage Loan
to the Seller or  Servicer as  applicable  and shall  execute  and deliver  such
instruments of transfer or assignment,  in each case without recourse,  as shall
be necessary to vest title (to the extent that such title was transferred to the
Trustee)  in the Seller or  Servicer  as  applicable,  or its  designee,  to any
Deleted Mortgage Loan substituted for pursuant to this Section 2.04.
          In any month in which the Seller or Servicer  substitutes  one or more
Replacement  Mortgage Loans for one or more Deleted Mortgage Loans, the Servicer
will determine the amount
                                      -46-
(if  any) by which  the  aggregate  Principal  Balance  of all such  Replacement
Mortgage  Loans  as of the  date of  substitution  is less  than  the  aggregate
Principal  Balance  of all such  Deleted  Mortgage  Loans  (in each  case  after
application of scheduled  principal  portion of the monthly payments received in
the month of substitution).  The amount of such shortage shall be deposited into
the  Custodial  Account by the Seller or Servicer  in the month of  substitution
pursuant to Section 3.07, without any reimbursement  thereof. The Servicer shall
give  notice in writing to the  Trustee of such  event,  which  notice  shall be
accompanied  by a Certificate  of a Servicing  Officer as to the  calculation of
such shortage.
          In the event that the Seller or  Servicer  shall  have  repurchased  a
Mortgage  Loan,  upon  receipt by the  Trustee of  written  notification  of the
deposit  of the  Purchase  Price,  the  Trustee  shall  release,  or cause to be
released,  the  related  Trustee  Mortgage  File  held  for the  benefit  of the
Certificateholders to the Seller or Servicer as applicable and the Trustee shall
execute and deliver the related  instruments of transfer or assignment,  in each
case without  recourse,  as shall be necessary to transfer  title (to the extent
that such title was transferred to the Trustee) from the Trustee for the benefit
of the  Certificateholders  and vest  title in the  Seller or  Servicer,  or the
designee thereof, as the case may be, to any Mortgage Loan purchased pursuant to
this Section 2.04. It is understood  and agreed that the  obligation  under this
Agreement of any Person to  repurchase  or  substitute  any Mortgage  Loan as to
which such breach has occurred and is continuing  shall  constitute the sole and
exclusive remedy respecting such breach available to  Certificateholders  or the
Trustee on their behalf.
     SECTION 2.05 ISSUANCE OF CERTIFICATES.
          The Trustee  acknowledges  the  assignment to it of the Mortgage Loans
together  with the  assignment  to it of all other assets  included in the Trust
Fund,  receipt  of which is  hereby  acknowledged.  Concurrently  (i) with  such
assignment  and delivery,  the Trustee,  pursuant to the written  request of the
Depositor  executed by an officer of the  Depositor,  has  executed  the Class A
Certificates and Class R Certificates and (ii)  concurrently,  with the delivery
of the Class A-1,  Class A-2,  Class A-3 and Class A-4  Certificates,  as of the
Class AR5 Delivery  Date,  the Trustee,  pursuant to the written  request of the
Depositor  executed by an officer of the  Depositor,  has executed the Class I-A
Certificates,  the Class B Certificates  and Class I-R  Certificates  and caused
them to be authenticated  and delivered to or upon the order of the Depositor in
authorized  denominations which evidence ownership of the Trust Fund. The rights
of the  Holders of such  Certificates  to receive  distributions  from the Trust
REMIC,  REMIC I or  REMIC  II,  as  applicable,  shall  be as set  forth in this
Agreement.
     SECTION 2.06 REMIC PROVISIONS.
          (a) The Depositor  hereby elects and  authorizes  the Trustee to treat
the Trust  REMIC,  REMIC I and  ▇▇▇▇▇ ▇▇ as a real  estate  mortgage  investment
conduit  under the Code and,  if  necessary,  under  applicable  state law.  The
Trustee shall make such election on Form 1066 or other  appropriate  federal tax
or information  return (including Form 8811) or any appropriate state return (x)
for the taxable  year ending on the last day of the  calendar  year in which the
Certificates  are issued  and (y) by an  attachment  making  such  election  and
stating that such election is being made as a protective matter, for the taxable
year  ending on the last day of the  calendar  year in which all or a portion of
the Certificates are first sold by Washington  Mutual to any party other than an
affiliate.  The  Delivery  Date is hereby  designated  as the  "startup  day" (a
"Startup Day") of the Trust REMIC
                                      -47-
and the Class AR5  Delivery  Date is hereby  designated  as the  "startup day (a
"Startup  Day") for REMIC I and REMIC II, in each case,  within  the  meaning of
Section  860G(a)(9)  of the Code for purposes of the election  made under clause
(x) of the preceding  sentence and the date of the first sale of Certificates by
Washington  Mutual to any party other than an affiliate is hereby  designated as
the "startup day" for purposes of the protective election to be made pursuant to
clause (y) of the  preceding  sentence.  The  "regular  interests"  (within  the
meaning of Section  860G of the Code) in the Trust  REMIC  shall  consist of the
Class A  Certificates  and the  "residual  interest"  in the Trust  REMIC  shall
consist of the Class R  Certificates.  The  Depositor  and the Trustee shall not
permit the  creation of any  "interests"  (within the meaning of Section 860G of
the Code) in the Trust  REMIC  other than the Class A and Class R  Certificates.
The  "regular  interests"  (within the  meaning of Section  860G of the Code) in
REMIC I shall consist of the Class AR5 Regular Interests and the Class Y Regular
Interests and the "residual  interest" in REMIC I shall consist of the Class R-I
Component.  The  Depositor  and the Trustee shall not permit the creation of any
"interests"  (within the  meaning of Section  860G of the Code) in REMIC I other
than the  regular  interests  therein  and Class  R-I  Component.  The  "regular
interests"  (within the  meaning of Section  860G of the Code) in REMIC II shall
consist  of the  Class  I-A  and  the  Class B  Certificates  and the  "residual
interest" in REMIC II shall consist of the Class R-II  Component.  The Depositor
and the Trustee  shall not permit the  creation of any  "interests"  (within the
meaning  of  Section  860G of the Code) in REMIC II other than the Class I-A and
Class B Certificates and the Class R-II Component.
          (b)  The  Seller,  (i)  on  behalf  of the  Holders  of  the  Class  R
Certificates,  shall act as agent for the Class R Certificateholder  and (ii) on
behalf of the Holders of the Class I-R Certificates,  shall act as agent for the
Class I-R  Certificateholder  and shall act as the "tax matters  person" (within
the meaning of the REMIC Provisions) for the Trust REMIC,  REMIC I and REMIC II,
as  applicable,  in the  manner  provided  under  Treasury  regulations  section
1.860F-4(d) and temporary Treasury regulations section 301.6231(a)(7)-1T. By its
acceptance of a Class R Certificate  and I-R  Certificate,  each Holder  thereof
shall  have  agreed  to  such  appointment  and  shall  have  consented  to  the
appointment  of the  Trustee  as its agent to act on behalf of the Trust  REMIC,
REMIC I and REMIC II, as applicable,  pursuant to the specific  duties  outlined
herein.
          (c) A  Holder  of  any  of the  Class  R  Certificates  or  Class  I-R
Certificates  by the  purchase  of such  Certificates,  shall be  deemed to have
agreed to timely  pay,  upon  demand by the  Trustee,  the amount of any minimum
California state franchise taxes due with respect to the Trust REMIC, REMIC I or
REMIC II, as applicable,  under Sections 23151(a) and 23153(a) of the California
Revenue and Taxation Code.  Notwithstanding the foregoing,  the Trustee shall be
authorized to retain the amount of such tax from amounts otherwise distributable
to such Holder in the event such Holder does not  promptly  pay such amount upon
demand by the Trustee.  In the event that any other federal,  state or local tax
is  imposed,  including  without  limitation  taxes  imposed  on  a  "prohibited
transaction"  of a REMIC as defined in Section 860F of the Code,  such tax shall
be  charged  against  amounts  otherwise   available  for  distribution  to  the
applicable  Holder  of a Class R or I-R  Certificate  and then  against  amounts
otherwise  available for distribution to the Holders of Regular  Certificates in
accordance   with  the   provisions   set  forth  in  Sections  4.02  and  4.03,
respectively.  The Trustee shall promptly deposit in the Certificate Account any
amount  of  "prohibited  transaction"  tax that  results  from a  breach  of the
Trustee's  duties under this Agreement.  The Servicer shall promptly  deposit in
the Certificate Account any amount of "prohibited  transaction" tax that results
from a breach of the Servicer's duties under this Agreement.
                                      -48-
          (d) The Trustee shall act as  attorney-in-fact  and as agent on behalf
of the tax matters  person of the Trust REMIC,  REMIC I and REMIC II and in such
capacity the Trustee shall: (i) prepare, sign and file, or cause to be prepared,
signed and filed,  federal  and state tax returns  using a calendar  year as the
taxable year for the Trust  REMIC,  REMIC I and REMIC II when and as required by
the REMIC Provisions and other applicable  federal income tax laws as the direct
representative  of the Trust REMIC,  REMIC I and REMIC II in compliance with the
Code and shall provide copies of such returns as required by the Code; (ii) make
an election,  on behalf of the Trust REMIC,  REMIC I and REMIC II, to be treated
as a REMIC on the  federal tax return of the Trust  REMIC,  REMIC I and REMIC II
for its first taxable year, in accordance with the REMIC  Provisions;  and (iii)
prepare  and  forward,   or  cause  to  be  prepared  and   forwarded,   to  the
Certificateholders  and to any  governmental  taxing  authority all  information
reports as and when required to be provided to them in accordance with the REMIC
Provisions and the Code. The expenses of preparing and filing such returns shall
be borne by the Trustee.  The Depositor  and Servicer  shall provide on a prompt
and timely basis to the Trustee or its designee such information with respect to
the Trust REMIC as is in their  possession and reasonably  required or requested
by the Trustee to enable it to perform its obligations under this subsection.
          In its capacity as attorney-in-fact  and as agent on behalf of the tax
matters  person,  the Trustee shall also:  (A) act on behalf of the Trust REMIC,
REMIC I and REMIC II in relation to any tax matter or controversy  involving the
Trust Fund,  (B)  represent  the Trust Funds in any  administrative  or judicial
proceeding  relating  to an  examination  or  audit by any  governmental  taxing
authority with respect  thereto and (C) cause to be paid solely from the sources
provided herein the amount of any taxes imposed on the Trust REMIC,  REMIC I and
REMIC II when and as the same  shall be due and  payable  (but  such  obligation
shall not prevent the Trustee or any other  appropriate  Person from  contesting
any such tax in appropriate  proceedings  and shall not prevent the Trustee from
withholding  payment of such tax, if  permitted  by law,  pending the outcome of
such proceedings).  The expense of any such representation shall be borne by the
Holders  of the Class R  Certificates  and Class I-R  Certificates  unless  such
expense is caused by a breach of the Trustee's  duties or the Servicer's  duties
hereunder,  in which  case such  expenses  shall be borne by the  Trustee or the
Servicer, as the case may be.
          (e) The  Trustee  shall  provide  (i) to any  transferor  of a Class R
Certificate and Class I-R Certificate  such  information as is necessary for the
application  of any tax relating to the transfer of a Class R Certificate to any
Person who is not a permitted transferee,  (ii) to the  Certificateholders  such
information  or  reports  as are  required  by the Code or the REMIC  Provisions
including  reports  relating to  interest,  original  issue  discount and market
discount or premium and (iii) to the Internal  Revenue Service the name,  title,
address and telephone number of the person who will serve as the  representative
of the Trust REMIC, REMIC I and REMIC II.
          (f) The Trustee, the Depositor, the Holder of the Class R Certificates
and the Holder of the Class I-R Certificates  shall take any action or cause the
Trust Fund to take any action  necessary to create or maintain the status of the
Trust REMIC, REMIC I or REMIC II as a REMIC under the REMIC Provisions and shall
assist each other as  necessary to create or maintain  such status.  Neither the
Trustee  nor the Holder of the Class R  Certificates  or the Holder of the Class
I-R Certificates shall take any action,  cause the Trust Fund to take any action
or fail to take (or fail to cause the Trust Fund to take) any action that, under
the  REMIC  Provisions,  if taken or not  taken,  as the case may be,  could (i)
endanger  the  status  of the  Trust  REMIC  as a REMIC  or (ii)  result  in the
imposition of a tax upon the Trust REMIC,  REMIC I or REMIC II  (including,  but
not limited to,
                                      -49-
the tax on prohibited transactions as defined in Code Section 860F(a)(2) and the
tax on  prohibited  contributions  set  forth in  Section  860G(d)  of the Code)
(either such event, an "Adverse REMIC Event") unless the Trustee has received an
Opinion of Counsel (at the expense of the party  seeking to take such action) to
the effect that the contemplated  action will not endanger such status or result
in the imposition of such a tax.
          The Trustee shall not take or fail to take any action  (whether or not
authorized  hereunder)  as to which the Servicer or Depositor  has advised it in
writing that it has received an Opinion of Counsel to the effect that an Adverse
REMIC Event could  occur with  respect to such  action.  In  addition,  prior to
taking any action with  respect to the Trust  REMIC,  REMIC I or REMIC II or its
respective  assets, or causing the Trust REMIC,  REMIC I or REMIC II to take any
action, which is not expressly permitted under the terms of this Agreement,  the
Trustee will consult with the  Servicer  and  Depositor or their  designees,  in
writing,  with respect to whether such action could cause an Adverse REMIC Event
to occur with respect to the Trust  REMIC,  REMIC I or REMIC II, and the Trustee
shall not take any such action or cause the Trust REMIC,  REMIC I or REMIC II to
take any such  action as to which the  Servicer or  Depositor  has advised it in
writing that an Adverse REMIC Event could occur.
          In  addition,  prior to taking  any action  with  respect to the Trust
REMIC or the assets therein,  or causing the Trust REMIC, REMIC I or REMIC II to
take any  action,  which is not  expressly  permitted  under  the  terms of this
Agreement,  the Holders of the Class R Certificates and the Holders of the Class
I-R Certificates will consult with the Trustee or its designee, in writing, with
respect to whether such action could cause an Adverse  REMIC Event to occur with
respect to the Trust  REMIC,  REMIC I or REMIC II, and no such Person shall take
any  action  or cause  the  Trust  Fund to take any such  action as to which the
Trustee has advised it in writing that an Adverse  REMIC Event could occur.  The
Trustee may consult with counsel to make such  written  advice,  and the cost of
same shall be borne by the party  seeking to take action not  permitted  by this
Agreement.
          At all times as may be required by the Code,  the Servicer will to the
extent  within its  control and the scope of its duties  more  specifically  set
forth herein, maintain substantially all of the assets of the Trust REMIC, REMIC
I or REMIC II as "qualified  mortgages" as defined in Section  860G(a)(3) of the
Code and "permitted investments" as defined in Section 860G(a)(5) of the Code.
          (g) In the event that any tax is imposed on "prohibited  transactions"
of the Trust REMIC, REMIC I or REMIC II, as defined in Section 860F(a)(2) of the
Code, on "net income from foreclosure  property" of the Trust REMIC,  REMIC I or
REMIC II, as defined in Section 860G(c) of the Code, on any contributions to the
Trust  REMIC,  REMIC I or REMIC II after the  applicable  Startup  Day  therefor
pursuant to Section 860G(d) of the Code, or any other tax is imposed by the Code
or any  applicable  provisions  of state or local  tax  laws,  such tax shall be
charged (i) to the Servicer,  if such tax arises out of or results from a breach
by the  Servicer  of  any of its  obligations  under  this  Agreement  or if the
Servicer  has in its sole  discretion  determined  to  indemnify  the Trust Fund
against such tax, (ii) to the Trustee, if such tax arises out of or results from
a breach by the  Trustee of any of its  obligations  under this  Article  II, or
(iii) otherwise  against amounts on deposit in the Custodial Account as provided
by Section 3.09 and on the Distribution Date(s) following such reimbursement the
aggregate  of such  taxes  shall  be  allocated  in  reduction  of the  Interest
Distribution Amount on each Class entitled thereto in the same manner as if such
taxes constituted a Prepayment Interest Shortfall.
                                      -50-
          (h) The  Trustee  and the  Servicer  shall,  for  federal  income  tax
purposes,  maintain  books and records with respect to the Trust REMIC,  REMIC I
and REMIC II on a calendar  year and on an accrual  basis or as otherwise may be
required by the REMIC Provisions.
          (i) Following the applicable Startup Day, neither the Servicer nor the
Trustee shall accept any contributions of assets to the Trust REMIC,  REMIC I or
REMIC II  (other  than a  Replacement  Mortgage  Loan  subject  to the terms and
conditions  herein)  unless the Servicer and the Trustee  shall have received an
Opinion  of  Counsel  (at  the  expense  of  the  party  seeking  to  make  such
contribution)  to the  effect  that the  inclusion  of such  assets in the Trust
REMIC,  REMIC I or REMIC II will not cause the Trust REMIC to fail to qualify as
a REMIC at any time that any Certificates are outstanding,  or subject the Trust
REMIC,  REMIC I or REMIC  II to any tax  under  the  REMIC  Provisions  or other
applicable provisions of federal, state and local law or ordinances.
          (j)  Neither  the  Servicer  nor the  Trustee  shall  enter  into  any
arrangement  by which the Trust REMIC will  receive a fee or other  compensation
for  services  nor permit the Trust  REMIC,  REMIC I or REMIC II to receive  any
income  from  assets  other  than  "qualified  mortgages"  as defined in Section
860G(a)(3)  of the  Code  or  "permitted  investments"  as  defined  in  Section
860G(a)(5) of the Code.
          (k) Within 30 days after the Delivery Date or Class AR5 Delivery Date,
as  applicable,  the Trustee  shall  prepare and file with the Internal  Revenue
Service  Form 8811,  "Information  Return for Real  Estate  Mortgage  Investment
Conduits (REMIC) and Issuers of  Collateralized  Debt Obligations" for the Trust
REMIC, REMIC I or REMIC II.
          (l) Neither the Trustee  nor the  Servicer  shall sell,  dispose of or
substitute  for any of the Mortgage  Loans  (except in  connection  with (i) the
default,  imminent default or foreclosure of a Mortgage Loan,  including but not
limited to, the acquisition or sale of a Mortgaged  Property acquired by deed in
lieu of  foreclosure,  (ii) the bankruptcy of the Trust REMIC,  REMIC I or REMIC
II,  (iii) the  termination  of the Trust  REMIC  pursuant  to Article X of this
Agreement or (iv) a purchase of Mortgage  Loans pursuant to Article II or III of
this Agreement) nor acquire any assets for the Trust REMIC,  nor sell or dispose
of any investments in the Custodial Account or the Certificate  Account for gain
nor accept any  contributions  to the Trust  REMIC  after the  Closing  Date (a)
unless it has  received  an  Opinion of  Counsel  that such  sale,  disposition,
substitution  or acquisition  will not affect  adversely the status of the Trust
REMIC,  REMIC I or REMIC II as a REMIC or (b) unless the Servicer has determined
in its sole discretion to indemnify the Trust Fund against such tax.
          (m) In order to enable the  Trustee to perform its duties as set forth
herein,  the Depositor  shall  provide,  or cause to be provided to the Trustee,
within  ten  days  after  the  Delivery  Date or Class  AR5  Delivery  Date,  as
applicable,  all information or data that the Trustee  determines to be relevant
for tax  purposes to the  valuations  and offering  prices of the  Certificates,
including,  without  limitation,  the price,  yield,  prepayment  assumption and
projected cash flows of the  Certificates and the Mortgage Loans and the Trustee
shall be  entitled  to rely  upon any and all such  information  and data in the
performance  of its duties set forth  herein.  Thereafter,  the  Servicer  shall
provide, promptly upon request therefor, any such additional information or data
that the Trustee may from time to time reasonably request in order to enable the
Trustee to  perform  its duties as set forth  herein  and the  Trustee  shall be
entitled to rely upon any and all such  information  and data in the performance
of its duties set forth herein.  The Depositor  shall  indemnify the Trustee and
hold
                                      -51-
it harmless  for any loss,  liability,  damage,  claim or expense of the Trustee
arising  from  any  failure  of the  Depositor  to  provide,  or to  cause to be
provided,  accurate  information  or data to the Trustee on a timely basis.  The
Servicer  shall  indemnify  the  Trustee  and  hold it  harmless  for any  loss,
liability,  damage,  claim or expense of the Trustee arising from any failure of
the Servicer to provide,  or to cause to be provided,  accurate  information  or
data to the Trustee on a timely basis. The indemnification  provisions hereunder
shall  survive  the  termination  of this  Agreement  and  shall  extend  to any
co-trustee appointed pursuant to this Agreement.
                                  ARTICLE III
                          ADMINISTRATION AND SERVICING
                                OF MORTGAGE LOANS
     SECTION 3.01 SERVICING STANDARD.
          For and on  behalf  of the  Trustee  and the  Certificateholders,  the
Servicer  shall service and  administer  the Mortgage  Loans in accordance  with
prudent mortgage loan servicing  standards and procedures  generally accepted in
the mortgage banking  industry and generally in a manner  consistent with ▇▇▇▇▇▇
▇▇▇ guidelines  except as otherwise  expressly  provided in this  Agreement.  In
connection with such servicing and administration,  the Servicer shall have full
power and authority, acting alone and/or through any Sub-Servicer as provided in
Section  3.02  hereof,  to do or cause to be done any and all things that it may
deem   necessary  or   desirable  in   connection   with  such   servicing   and
administration,  including but not limited to, the power and authority,  subject
to  the  terms   hereof  (a)  to  execute   and   deliver,   on  behalf  of  the
Certificateholders  and the  Trustee,  customary  consents  or waivers and other
instruments   and   documents   (including,    without   limitation,    estoppel
certificates),  (b) to  consent  to  transfers  of any  Mortgaged  Property  and
assumptions of the Mortgage Notes and related  Mortgages (but only in the manner
provided  in  this  Agreement),  (c)  to  collect  any  Insurance  Proceeds  and
Liquidation Proceeds, (d) to consent to any subordinate financings to be secured
by any Mortgaged  Property to the extent that such consent is required  pursuant
to the terms of the related  Mortgage,  (e) to consent to the application of any
proceeds of insurance policies or condemnation  awards to the restoration of the
applicable Mortgaged Property or otherwise, and (f) subject to the provisions of
Section 3.07 and 3.13,  to  effectuate  foreclosure  or other  conversion of the
ownership  of the  Mortgage  Property  securing  any  Mortgage  Loan;  provided,
however, that the Servicer shall take no action that is materially  inconsistent
with  or   materially   prejudices   the   interest   of  the   Trustee  or  the
Certificateholders  in any  Mortgage  Loan or the  rights  and  interest  of the
Depositor,  the  Trustee  and the  Certificateholders  under  the  terms of this
Agreement unless such action is specifically called for by the terms hereof.
          Without  limiting the generality of the foregoing,  but subject to the
terms hereof,  the Servicer,  in its own name or in the name of the Trustee,  is
hereby  authorized  and  empowered by the  Depositor  and the Trustee,  when the
Servicer  believes it appropriate in its best judgment,  to execute and deliver,
on behalf of the Trustee,  the  Certificateholders  or any of them,  any and all
instruments of  modification,  satisfaction,  cancellation or assignment,  or of
partial or full release or discharge and all other comparable instruments,  with
respect to the Mortgage Loans, and with respect to the Mortgaged Properties held
for the benefit of the  Certificateholders.  The Servicer shall promptly  notify
the Trustee of any such  execution and delivery.  The Trustee for the benefit of
the  Certificateholders  shall  furnish the Servicer with any powers of attorney
and other  documents  necessary or appropriate to enable the Servicer to service
and administer the Mortgage Loans.
                                      -52-
          Notwithstanding  anything  in  this  Agreement  to the  contrary,  the
Servicer  shall not  (unless the  Mortgagor  is in default  with  respect to the
Mortgage  Loan or such  default is, in the judgment of the  Servicer,  imminent)
permit any modification  with respect to any Mortgage Loan (i) that would change
the Net Mortgage Rate or Class AR5 Net Mortgage Rate, as applicable,  or, reduce
or increase the principal  balance (except for reductions  resulting from actual
payments of principal) or (ii) that would both  constitute a sale or exchange of
such Mortgage Loan within the meaning of Section 1001 of the Code (including any
proposed,  temporary or final regulations promulgated thereunder) (other than in
connection  with a proposed  conveyance or assumption of such Mortgage Loan that
is a  Principal  Prepayment  made (or treated as made) by the  Mortgagor  of the
entire principal balance of a Mortgage Loan) and cause an Adverse REMIC Event.
     SECTION 3.02 ENFORCEMENT OF THE OBLIGATIONS OF SUB-SERVICERS.
          (a) For purposes of this  Agreement,  the Servicer  shall be deemed to
have  received the payments on the Mortgage  Loans  referred to in Sections 3.07
and 3.08  hereof  when the  related  Sub-Servicer,  if any,  has  received  such
payments and shall remain  obligated to deposit such payments in accordance with
Sections 3.07 and 3.08 hereof,  regardless of whether such payments are remitted
by the Sub-Servicer to the Servicer.  The Servicer and the related  Sub-Servicer
may enter into amendments to any applicable Sub-Servicing  Agreement;  provided,
however, that any such amendments shall be consistent with and shall not violate
the provisions of this Agreement.
          (b) As part of its servicing activities hereunder,  the Servicer,  for
the benefit of the  Depositor,  the Trustee  and the  Certificateholders,  shall
supervise,  administer,  monitor and oversee the servicing of the Mortgage Loans
that are not serviced by it directly,  and shall enforce the obligations of each
Sub-Servicer,   if  any,  under  the  related  Sub-Servicing   Agreement.   Such
enforcement shall include, without limitation,  the legal prosecution of claims,
termination of  Sub-Servicing  Agreements,  as  appropriate,  and the pursuit of
other appropriate remedies, and shall be in such form and carried out to such an
extent and at such time as the Servicer,  in its good faith  business  judgment,
would  require  were it the owner of the related  Mortgage  Loans.  The Servicer
shall  pay the  costs  of such  enforcement  at its own  expense,  but  shall be
reimbursed  therefor  only (i)  from a  general  recovery  resulting  from  such
enforcement  only to the extent,  if any, that such recovery exceeds all amounts
due in respect of the related Mortgage Loans or (ii) from a specific recovery of
costs,   expenses  or  attorneys  fees  against  the  party  against  whom  such
enforcement is directed.  The Servicer shall not waive any event of default by a
Sub-Servicer  under a  Sub-Servicing  Agreement  which is a failure to remit any
payment required to be made by such  Sub-Servicer  that would result in an Event
of Default under this Agreement.
          (c) During the term of this  Agreement,  the  Servicer  shall  consult
fully with each of the  Sub-Servicers  as may be necessary  from time to time to
perform and carry out the Servicer's  obligations hereunder and receive,  review
and evaluate all  reports,  information  and other data that are provided to the
Servicer by each Sub-Servicer and otherwise exercise reasonable efforts to cause
each  Sub-Servicer  to  perform  and  observe  the  covenants,  obligations  and
conditions to be performed or observed by it under its Sub-Servicing Agreement.
     SECTION 3.03 TERMINATION OF THE RIGHTS OF SUB-SERVICERS.
          If the  Servicer  terminates  the rights of a  Sub-Servicer  under any
Sub-Servicing  Agreement, the Servicer shall service the Mortgage Loans directly
pursuant to and in accordance
                                      -53-
with the terms of this Agreement,  or at the Servicer's  election,  enter into a
substitute  servicing  agreement with another  mortgage loan  servicing  company
reasonably  acceptable to the Servicer  under which such mortgage loan servicing
company shall assume,  satisfy,  perform and carry out all liabilities,  duties,
responsibilities and obligations that are to be, or otherwise were to have been,
satisfied, performed and carried out by the terminated Sub-Servicer,  regardless
of whether such liabilities,  duties, responsibilities or obligations shall have
accrued  before or after the  termination  of the  rights of such  Sub-Servicer;
PROVIDED,  HOWEVER,  that any such  substitute  servicer and any such substitute
servicing  shall  satisfy the  requirements  of Sections  3.01 and 3.02.  If the
Servicer does not elect to enter into a substitute  servicing  agreement  with a
successor servicer,  the Servicer shall nevertheless  service the Mortgage Loans
directly pursuant to and in accordance with the terms of this Agreement, until a
substitute  Sub-Servicer  has been  appointed  and  designated  and a substitute
servicing  agreement  has been entered into by the Servicer and such  substitute
Sub-Servicer.
     SECTION 3.04 LIABILITY OF THE SERVICER.
          Notwithstanding the provisions of any Sub-Servicing  Agreement, any of
the provisions of this Agreement relating to agreements or arrangements  between
the  Servicer  or a  Sub-Servicer  or  reference  to  actions  taken  through  a
Sub-Servicer or otherwise, the Servicer shall remain obligated and liable to the
Depositor,  the  Trustee  and  the  Certificateholders  for  the  servicing  and
administering  of the Mortgage  Loans  included in the Trust Fund in  accordance
with (and subject to the  limitations  contained  within) the provisions of this
Agreement  without  diminution of such obligation or liability by virtue of such
Sub-Servicing   Agreements  or  agreements  or  arrangements  or  by  virtue  of
indemnification  from the Sub-Servicer and to the same extent and under the same
terms and conditions as if the Servicer  alone were servicing and  administering
the Mortgage  Loans.  The Servicer shall be entitled to enter into any agreement
with a Sub-Servicer for indemnification of the Servicer and nothing contained in
this Agreement shall be deemed to limit or modify such indemnification.
     SECTION  3.05  RIGHTS OF THE  DEPOSITOR  AND THE  TRUSTEE IN RESPECT OF THE
SERVICER.
          The Servicer  shall  afford the  Depositor  and the  Trustee,  without
charge but only upon reasonable notice and during normal business hours,  access
to all records and  documentation  in the  Servicer's  possession  regarding the
Mortgage Loans and to all accounts,  insurance policies and other matters in the
Servicer's  possession  relating to this Agreement and access to officers of the
Servicer  responsible for its obligations  hereunder.  The Depositor may, but is
not  obligated  to,  enforce the  obligations  of the  Servicer  hereunder.  The
Depositor  shall not have any  responsibility  or  liability  for any  action or
failure to act by the Servicer and is not obligated to supervise the performance
of the Servicer hereunder or otherwise.
     SECTION 3.06 TRUSTEE TO ACT AS SERVICER.
          In the event that the  Servicer  shall for any reason no longer be the
Servicer  hereunder  (including  by reason of an Event of Default),  the Trustee
shall  thereupon  assume  all of the  rights  and  obligations  of the  Servicer
hereunder  arising  thereafter  (except that the Trustee shall not be liable for
losses  in  connection  with  Eligible  Investments  required  to be paid by the
Servicer  pursuant to Section  3.07 or 4.01  hereof,  obligated  to make Monthly
Advances if  prohibited  by applicable  law, nor to  effectuate  repurchases  or
substitutions  of Mortgage  Loans  hereunder as substitute  Servicer,  including
pursuant to Section 2.04 hereof and except that the Trustee makes no
                                      -54-
representations  and warranties  hereunder,  including  pursuant to Section 2.04
hereof).  If the  Servicer  shall  for any  reason  no  longer  be the  Servicer
(including  by  reason  of any  Event of  Default),  the  Trustee  (or any other
successor  servicer) shall succeed to any rights and obligations of the Servicer
under any  Sub-Servicing  Agreement  and shall be  deemed  to have  assumed  the
Servicer's  interest  therein;  PROVIDED,  HOWEVER,  that the Servicer shall not
thereby be relieved of any liability or obligations  under this  Agreement,  any
Sub-Servicing  or substitute  servicing  agreement  arising prior to the date of
such succession.
          The Servicer shall, upon request of the Trustee, but at the expense of
the Servicer,  deliver to the assuming party all documents and records  relating
to the  Mortgage  Loans then being  serviced  thereunder  and an  accounting  of
amounts  collected  and held by it and  otherwise use its best efforts to effect
the orderly and efficient transfer of servicing to the assuming party.
     SECTION 3.07 COLLECTION OF MORTGAGE LOAN PAYMENTS.
          The  Servicer  shall make  reasonable  efforts to collect all payments
called for under the terms and  provisions of the Mortgage  Loans and shall,  to
the extent such procedures shall be consistent with this Agreement,  follow such
collection procedures as it follows with respect to mortgage loans comparable to
the  Mortgage  Loans held in its own  portfolio  and  serviced by the  Servicer.
Consistent with the foregoing,  the Servicer may in its discretion (a) waive any
late payment charge or any prepayment  charge or penalty  interest in connection
with the  prepayment of a Mortgage  Loan and (b) subject to Section  3.01,  only
upon  determining that the coverage of such Mortgage Loan by any related Primary
Mortgage  Insurance  Policy  will not be  affected,  extend  the due  dates  for
payments due on a Mortgage  Note for a period not greater than 365 days,  but in
no event beyond the maturity date of any Mortgage Loan. In the event of any such
arrangement  described  in clause (b) of the  preceding  sentence,  the Servicer
shall  continue to make timely  Monthly  Advances on the related  Mortgage Loan,
pursuant to and in accordance  with Section 5.01 of this  Agreement (but subject
to any limitations contained therein), during the scheduled period in accordance
with the  amortization  schedule  of such  Mortgage  Loan  without  modification
thereof by reason of such arrangements.
          The Servicer  shall  establish and maintain,  in its name on behalf of
the  Certificateholders,  the Custodial Account. The Servicer shall deposit into
the Custodial  Account  within two Business Days of receipt by the Servicer,  or
receipt from the Sub-Servicers except as otherwise specifically provided herein,
the following payments and collections  received or made by it subsequent to the
Cut-off  Date (other than in respect of  principal of and interest and any other
payments on the Mortgage Loans due on or before the Cut-off Date):
               (i) all  payments on account of  principal,  including  Principal
Prepayments, on the Mortgage Loans;
               (ii) all  payments on account of interest on the  Mortgage  Loans
less the Servicing Fee and,  with respect to the Class AR5 Mortgage  Loans,  the
Additional Servicing Fee;
               (iii) all Insurance Proceeds and Liquidation Proceeds, other than
proceeds to be applied to the restoration or repair of the Mortgaged Property or
released to the Mortgagor in accordance  with the  Servicer's  normal  servicing
procedures,  net of Liquidation  Expenses,  unpaid  servicing  compensation  and
unreimbursed Monthly Advances;
                                      -55-
               (iv) any amount of any losses  required  to be  deposited  by the
Servicer  pursuant to the second  succeeding  paragraph  of this Section 3.07 in
connection with any losses on Eligible Investments;
               (v) any amounts required to be deposited by the Servicer pursuant
to Section 3.11 hereof;
               (vi) all proceeds of any purchase by the Seller or the  Servicer,
as the case may be, of any Mortgage Loans or property acquired in respect of the
Mortgage Loans pursuant to Sections 2.01, 2.02, 2.03, 2.04, 3.12 or 10.01 hereof
and all amounts  required to be deposited in connection with the substitution of
Replacement  Mortgage Loans pursuant to Sections 2.01,  2.02, 2.03, 2.04 or 3.12
hereof; and
               (vii) any other amounts required to be deposited in the Custodial
Account pursuant to this Agreement  including,  without limitation,  the amounts
required to be deposited therein pursuant to Section 3.13 hereof.
          The foregoing  requirements  for  remittance by the Servicer  shall be
exclusive,  it being understood and agreed that, without limiting the generality
of the foregoing,  the Servicing Fee, the Additional  Servicing Fee, payments in
the nature of prepayment penalties,  fees or premiums,  late payment charges and
assumption  fees and any excess  interest  charges  payable by the  Mortgagor by
virtue of any default or other non-compliance by the Mortgagor with the terms of
the  Mortgage  or any  other  instrument  or  document  executed  in  connection
therewith or otherwise, if collected, need not be remitted or deposited into the
Custodial Account by the Servicer. Notwithstanding the foregoing, the Additional
Servicing Fee may only be retained from the Class AR5 Mortgage Loans for so long
as REMIC I is in  existence.  In the  event  that the  Servicer  shall  remit or
deposit any amount not  required to be remitted or deposited  and not  otherwise
subject to  withdrawal  pursuant  to  Section  3.09  hereof,  it may at any time
withdraw  such amount from the Custodial  Account on the following  Distribution
Date, any provision herein to the contrary  notwithstanding.  Such direction may
be  accomplished  by  delivering  a  Certificate  of a Servicing  Officer to the
Trustee which describes the amounts deposited in error in the Custodial Account.
All funds  deposited in the  Custodial  Account shall be held by the Servicer in
trust  for the  Certificateholders  until  disbursed  in  accordance  with  this
Agreement or withdrawn in  accordance  with Section  3.09. In no event shall the
Trustee  incur  liability  for  withdrawals  from the  Custodial  Account at the
direction of the Servicer.
          Any  investments of amounts on deposit in the Custodial  Account shall
be made by the  Servicer in Eligible  Investments,  which shall mature not later
than the second Business Day preceding the Distribution  Date following the date
of such investment (except that if such Eligible  Investment is an obligation of
the  institution  that  maintains  the  Custodial  Account,  then such  Eligible
Investment  shall  mature  not later  than  such  Distribution  Date).  All such
Eligible Investments shall be made in the name of the Trustee for the benefit of
the Certificateholders.  All income and gain net of any losses realized from any
such investment shall be for the benefit of the Servicer and shall be subject to
withdrawal at its direction  from time to time.  The amount of any losses net of
any gains incurred by the Servicer in respect of any such  investments  shall be
remitted  to the  Trustee  or  deposited  in the  Custodial  Account  out of the
Servicer's own funds promptly following the date the same are realized.
                                      -56-
          So long as the Class I-A Certificates and the Class B Certificates are
outstanding,  the Servicer shall promptly give notice to the Trustee, the Rating
Agencies and the Depositor of the location of the  Custodial  Account and of any
change thereof.
     SECTION 3.08  COLLECTION OF TAXES,  ASSESSMENTS  AND SIMILAR ITEMS;  ESCROW
ACCOUNTS.
          In addition to the Custodial Account, the Servicer shall establish and
maintain one or more custodial  accounts (each, an "Escrow Account") and deposit
and retain  therein all  collections  from the  Mortgagors  (or  advances by the
Servicer) for the payment of taxes, assessments and hazard insurance premiums or
comparable  items for the account of the  Mortgagors.  Escrow  Accounts shall be
Eligible  Accounts.  All  costs  incurred  by the  Servicer  or by  the  related
Sub-Servicer  in effecting the timely  payments of taxes and  assessments on the
Mortgaged  Properties and related insurance  premiums shall not, for the purpose
of calculating monthly distributions to the Certificateholders,  be added to the
Principal  Balance under the related  Mortgage Loans,  notwithstanding  that the
terms of such Mortgage Loans so permit.
          Withdrawals  of amounts so collected  from the Escrow  Accounts may be
made only to effect  timely  payment  of taxes,  assessments,  hazard  insurance
premiums or Primary  Mortgage  Insurance  Policy  premiums,  condominium  or PUD
association  dues, or comparable  items,  to reimburse the Servicer  pursuant to
Sections 3.10 hereof (with respect to the Primary Mortgage Insurance Policy) and
3.08  hereof  (with  respect to taxes and  assessments)  and 3.11  hereof  (with
respect to hazard  insurance),  to refund to any  Mortgagors  any sums as may be
determined  to be overages,  to pay  interest,  if required,  to  Mortgagors  on
balances in the Escrow  Account or to clear and terminate the Escrow  Account at
the  termination of this Agreement in accordance  with Section 10.01 hereof.  As
part of its servicing duties,  the Servicer shall, and the Sub-Servicers  shall,
pursuant to any Sub-Servicing  Agreement,  be required to, pay to the Mortgagors
interest on funds in the Escrow Account, to the extent required by law.
          The Servicer shall,  with respect to each Mortgage Loan, to the extent
any related Sub-Servicer does not do so, advance the payments referred to in the
preceding  paragraph  that  are not  timely  paid by the  Mortgagors;  PROVIDED,
HOWEVER,  that the  Servicer  shall be required to so advance only to the extent
that  such  advances,  in the  good  faith  judgment  of the  Servicer,  will be
recoverable by the Servicer out of Insurance Proceeds,  Liquidation  Proceeds or
otherwise out of the related  Mortgage  Loan;  and PROVIDED  FURTHER,  that such
payments  shall be advanced  when the tax,  premium or other cost for which such
payment is intended is due.
     SECTION 3.09 PERMITTED WITHDRAWALS FROM THE CUSTODIAL ACCOUNT.
          The  Servicer  may (and,  with  respect to clauses  (e) and (g) below,
shall),  from time to time,  direct the Trustee to make,  and the Trustee  shall
make,  to the extent  required or  authorized  hereunder,  withdrawals  from the
Custodial Account for the following purposes:
          (a) to pay to the  Servicer  from funds on  deposit  in the  Custodial
Account earnings on or investment  income with respect to funds in the Custodial
Account less losses referred to in Section 3.07(iv);
                                      -57-
          (b) to reimburse  the Servicer for advances  made pursuant to Sections
3.01, 3.08, 3.10, 3.11, 3.13, 5.01 and 5.02 hereof,  such right of reimbursement
pursuant to this  subclause (b) being limited to amounts  received in respect of
the particular Mortgage Loan (including,  for this purpose,  Insurance Proceeds,
Liquidation Proceeds, amounts representing proceeds of other insurance policies,
if any,  covering the related Mortgaged  Property,  rental and other income from
REO Property and proceeds of any purchase or repurchase of the related  Mortgage
Loan);
          (c) to reimburse the Servicer for any Nonrecoverable  Advances made in
respect of any Mortgage Loan, PROVIDED,  HOWEVER, that reimbursements in respect
of  Mortgage  Loans in Loan  Group 5, Loan  Group 6, Loan Group 7, Loan Group 8,
Loan Group 9 and the Class Y Mortgage  Loans may only  reimbursed  from  amounts
collected  with respect to Mortgage  Loans in such Loan Group or with respect to
the Class Y Mortgage Loans; and  reimbursements in respect of Class AR5 Mortgage
Loans may only  reimbursed  from  amounts  collected  on the Class AR5  Mortgage
Loans;
          (d)  to  reimburse   the  Servicer  from   Liquidation   Proceeds  for
Liquidation  Expenses and, to the extent that  Liquidation  Proceeds  after such
reimbursement  are in excess of the  Principal  Balance of the related  Mortgage
Loan  together with accrued and unpaid  interest  thereon at a rate equal to the
Net Mortgage Rate or Class AR5 Net Mortgage Rate, as  applicable,  to pay out of
such excess the amount of any unpaid servicing compensation to the Servicer with
respect  to  any  Mortgage  Loan,   which  may  include  any  unpaid   servicing
compensation to a Sub-Servicer (for disbursement in accordance with Section 3.16
hereof);
          (e) to pay to the  Seller or the  Servicer,  as the case may be,  with
respect to each Mortgage Loan or property  acquired in respect  thereof that has
been purchased  pursuant to Sections 2.01,  2.02,  2.03, 2.04 or 3.12 hereof all
amounts  received thereon and not taken into account in determining the Purchase
Price of such repurchased Mortgage Loan;
          (f) to reimburse the Servicer or the  Depositor for expenses  incurred
by and  reimbursable  to the Servicer or the Depositor  pursuant to Section 7.03
hereof;
          (g) to withdraw any amount deposited in the Custodial Account pursuant
to Section 3.07 and not required to be deposited therein; and
          (h) to clear and terminate the Custodial  Account upon  termination of
this  Agreement  pursuant to Section 10.01 hereof.  The Servicer  shall keep and
maintain separate accounting, on a Mortgage Loan by Mortgage Loan basis, for the
purpose of justifying any withdrawal from the Custodial Account pursuant to such
subclauses (b), (c), (d) and (e).
          On or prior to the Business Day preceding each Distribution Date after
payment of items (a) through (h) above,  the Servicer  shall  withdraw  from the
Custodial Account and remit to the Trustee, in immediately  available funds, and
the Trustee, upon receipt thereof,  shall deposit in the Certificate Account, an
amount equal to the Available Distribution Amount for such Distribution Date.
                                      -58-
     SECTION  3.10   MAINTENANCE  OF  PRIMARY   MORTGAGE   INSURANCE   POLICIES;
COLLECTIONS THEREUNDER.
          The Servicer shall not take, or permit any  Sub-Servicer  to take, any
action  that  would  result in loss of  coverage  under any  applicable  Primary
Mortgage  Insurance  Policy  for any  loss  which,  but for the  actions  of the
Servicer or Sub-Servicer, would have been covered thereunder.
          The Servicer shall keep in full force and effect each Primary Mortgage
Insurance  Policy  applicable to a Mortgage Loan being  serviced by it until the
principal  balance of the related  Mortgage Loan, in the case of a Mortgage Loan
having a Loan-to-Value  Ratio at origination in excess of 80%, is reduced to (a)
80% or less of the Appraised Value or (b) 80% or less of its current value based
on a new  appraisal.  The  Servicer  agrees  to pay to the  extent  the  related
Mortgagor  does not do so, the  premiums  for each  Primary  Mortgage  Insurance
Policy on a timely  basis and shall  use its best  reasonable  efforts  to cause
itself or the Sub-Servicer to be named as loss payee,  provided,  however,  that
the Servicer shall be required to pay such premiums only to the extent that such
advances, in the good faith judgment of the Servicer, will be recoverable by the
Servicer out of Insurance Proceeds, Liquidation Proceeds or otherwise out of the
related  Mortgage Loan. In the event that the insurer under any Primary Mortgage
Insurance  Policy shall cease to be  qualified  to transact a mortgage  guaranty
insurance  business under the laws of the state of its organization or any other
state  that  has   jurisdiction   over  such  insurer  (or  if  such   insurer's
claims-paying  ability  shall  adversely  affect  the  rating  on  the  Class  A
Certificates or the Class AR5  Certificates) or such Primary Mortgage  Insurance
Policy is cancelled or terminated  for any reason,  the Servicer  shall exercise
its best reasonable  efforts to obtain, or to cause the related  Sub-Servicer to
obtain,  from another Qualified Insurer, a replacement policy comparable to such
Primary Mortgage Insurance Policy at the expense of the Mortgagor.  The Servicer
shall not  consent to the  cancellation  or  refusal  to renew any such  Primary
Mortgage Insurance Policy applicable to any Mortgage Loan, which is in effect at
the date of the initial  issuance of the Certificates and is required to be kept
in force hereunder unless the replacement  Primary Mortgage Insurance Policy for
such cancelled or non-renewed policy is maintained with an insurer with a rating
not lower than the  insurer  issuing the Primary  Mortgage  Insurance  Policy in
effect  at the  date  of the  initial  issuance  of the  Certificates  or  whose
claims-paying will not adversely affect the rating on the Certificates or unless
any such cancellation or refusal, or consent thereto,  will not adversely affect
the  rating  on  the  Certificates.   In  connection  with  any  assumption  and
modification  agreement entered into by the Servicer or a Sub-Servicer  pursuant
to Section  3.12,  the Servicer  shall  obtain a  replacement  Primary  Mortgage
Insurance Policy, as provided above.
          In connection with its activities as administrator and servicer of the
Mortgage Loans, the Servicer agrees to present, on behalf of itself, the Trustee
for the  benefit  of the  Certificateholders,  claims to the  insurer  under any
Primary Mortgage Insurance Policies and, in this regard, to take such reasonable
action as shall be  necessary  to permit  recovery  under any  Primary  Mortgage
Insurance Policies respecting defaulted Mortgage Loans. Pursuant to Section 3.07
hereof,  any  amounts  collected  by the  Servicer  under any  Primary  Mortgage
Insurance  Policy  shall be  deposited  in the  Custodial  Account,  subject  to
withdrawal pursuant to Section 3.09 hereof.
                                      -59-
     SECTION 3.11 MAINTENANCE OF HAZARD INSURANCE AND OTHER INSURANCE.
          The Servicer  shall cause to be  maintained  for each  Mortgage  Loan,
hazard  insurance with extended  coverage in an amount that is at least equal to
the maximum  insurable value of improvements  securing such Mortgage Loan or its
Principal Balance, whichever is less.
          Each policy of standard  hazard  insurance  shall contain,  or have an
accompanying endorsement that contains, a standard mortgagee clause complying in
all material respects in form and substance to applicable ▇▇▇▇▇▇ ▇▇▇ guidelines.
The Servicer shall cause to be maintained on property  acquired upon foreclosure
or deed in lieu of foreclosure of any Mortgage Loan, liability insurance and, to
the extent  described below,  flood insurance.  Pursuant to Section 3.07 hereof,
any  amounts  collected  by the  Servicer  under any such  policies  (other than
amounts to be  applied to the  restoration  or repair of the  related  Mortgaged
Property  or property  thus  acquired or amounts  released to the  Mortgagor  in
accordance  with the terms of the applicable  Mortgage or the Servicer's  normal
servicing  procedures) shall be deposited in the Custodial  Account,  subject to
withdrawal pursuant to Section 3.09 hereof.
          Any cost  incurred  by the  Servicer or the  related  Sub-Servicer  in
maintaining any such insurance shall not, for the purpose of calculating monthly
distributions to the  Certificateholders or remittances to the Trustee for their
benefit, be added to the Principal Balance of the Mortgage Loan, notwithstanding
that the terms of the Mortgage Loan so permit.  Such costs shall be  recoverable
by the  Servicer  out of payments by the related  Mortgagor  or out of Insurance
Proceeds or Liquidation Proceeds to the extent permitted by Section 3.09 hereof.
If the Mortgaged  Property is located at the time of origination of the Mortgage
Loan in a federally  designated  special flood hazard area,  the Servicer  shall
cause flood  insurance to be  maintained.  Such flood  insurance  shall be in an
amount  equal to the lesser of (i) the unpaid  Principal  Balance of the related
Mortgage  Loan or (ii) the maximum  amount of such  insurance  available for the
related Mortgaged  Property under the national flood insurance  program,  if the
area in which  such  Mortgaged  Property  is located  is  participating  in such
program.  Notwithstanding  anything  in  this  paragraph  to the  contrary,  the
Servicer  shall  be  required  to  pay  the  costs  of  maintain  any  insurance
contemplated by this Section 3.11 only to the extent that such advances,  in the
good faith judgment of the Servicer,  will be recoverable by the Servicer out of
Insurance  Proceeds,  Liquidation  Proceeds  or  otherwise  out of  the  related
Mortgage Loan.
          In the event that the  Servicer  shall  obtain and  maintain a blanket
policy  insuring  against hazard losses on all of the Mortgage  Loans,  it shall
conclusively  be deemed to have  satisfied its  obligations  as set forth in the
first  sentence of this Section 3.11, it being  understood  and agreed that such
policy may contain a  deductible  clause on terms  substantially  equivalent  to
those  commercially  available  and  maintained  by  comparable  servicers,  and
provided that the provider of such blanket  policy is rated by A.M. Best Company
A:V or higher and the claims-paying  ability of such provider is rated in one of
the  three  highest  rating  categories  by at least one  nationally  recognized
statistical  rating  organization.  If such policy contains a deductible clause,
the Servicer  shall,  to the extent that there shall not have been maintained on
the related  Mortgaged  Property a policy  complying  with the first sentence of
this  Section 3.11 and there shall have been a loss that would have been covered
by such policy,  remit to the Trustee for deposit in the  Custodial  Account the
amount not otherwise payable under the blanket policy because of such deductible
clause,  accompanied  by a certificate  of a Servicing  Officer  describing  the
calculation of such amount.  In connection with its activities as  administrator
and servicer of the Mortgage Loans, the Servicer
                                      -60-
agrees to present, on behalf of itself, the Depositor,  the Trustee or its agent
for the benefit of the Certificateholders, claims under any such blanket policy.
     SECTION 3.12 ENFORCEMENT OF DUE-ON-SALE CLAUSES; ASSUMPTION AGREEMENTS.
          (a) Except as  otherwise  provided in this Section  3.12(a),  when any
property subject to a Mortgage has been conveyed by the Mortgagor,  the Servicer
shall,  to the extent  that it has  knowledge  of such  conveyance,  enforce any
due-on-sale  clause  contained in any Mortgage  Note or Mortgage,  to the extent
permitted under  applicable law and  governmental  regulations,  but only to the
extent that such enforcement  will not adversely  affect or jeopardize  coverage
under any  Required  Insurance  Policy.  In the event that the  Servicer  or the
related  Sub-Servicer  is prohibited by law from enforcing any such  due-on-sale
clause,  or if coverage under any Required  Insurance  Policy would be adversely
affected,  the Servicer is authorized,  subject to Section  3.12(b),  to take or
enter into an assumption and  modification  agreement from or with the person to
whom such  property has been or is about to be conveyed,  pursuant to which such
person  becomes  liable  under the  Mortgage  Note  and,  unless  prohibited  by
applicable  state law, the Mortgagor  remains liable thereon,  provided that the
Mortgage  Loan shall  continue to be covered (if so covered  before the Servicer
enters such  agreement)  by the  applicable  Required  Insurance  Policies.  The
Servicer, subject to Section 3.12(b), is also authorized with the prior approval
of  the  insurers  under  any  Required  Insurance  Policies  to  enter  into  a
substitution  of liability  agreement  with such  person,  pursuant to which the
original  Mortgagor is released from liability and such person is substituted as
Mortgagor  and becomes  liable  under the  Mortgage  Note.  Notwithstanding  the
foregoing,  the Servicer shall not be deemed to be in default under this Section
3.12(a) by reason of any transfer or assumption which the Servicer is restricted
by law from preventing, for any reason whatsoever.
          (b) Subject to the Servicer's duty to enforce any  due-on-sale  clause
to the  extent  set  forth in  Section  3.12(a)  hereof,  in any case in which a
Mortgaged  Property  has  been  conveyed  to a  Person  by a  Mortgagor,  if  an
assumption is permitted  under Section  3.12(a) and such Person is to enter into
an assumption agreement or modification  agreement or supplement to the Mortgage
Note or Mortgage  held for the benefit of the  Certificateholders  that requires
the  signature  of the Trustee,  or if an  instrument  of release  signed by the
Trustee is required releasing the Mortgagor from liability on the Mortgage Loan,
the Servicer shall deliver or cause to be delivered to the Trustee for signature
the assumption agreement with the Person to whom the Mortgaged Property is to be
conveyed and such  modification  agreement or supplement to the Mortgage Note or
Mortgage or other  instruments  as are  reasonable or necessary to carry out the
terms  of the  Mortgage  Note or  Mortgage  or  otherwise  to  comply  with  any
applicable laws regarding  assumptions or the transfer of the Mortgaged Property
to such Person.  The Servicer shall also deliver or cause to be delivered to the
Trustee  with the  foregoing  documents a letter  explaining  the nature of such
documents and the reason or reasons why the Trustee's signature is required.
          With  such  letter,  the  Servicer  shall  deliver  to the  Trustee  a
certificate of a Servicing Officer  certifying that: (i) a Servicing Officer has
examined  and  approved  such  documents  as to form  and  substance,  (ii)  the
Trustee's  execution and delivery  thereof will not conflict with or violate any
terms of this Agreement or cause the unpaid balance and interest on the Mortgage
Loan to be  uncollectible  in whole or in part,  (iii) any required  consents of
insurers  under any  Required  Insurance  Policies  have been  obtained and (iv)
subsequent  to the  closing  of the  transaction  involving  the  assumption  or
transfer (A) the Mortgage Loan will  continue to be secured by a first  mortgage
lien  pursuant  to the  terms of the  Mortgage,  (B) such  transaction  will not
adversely affect the
                                      -61-
coverage under any Required Insurance Policies, (C) the Mortgage Loan will fully
amortize over the remaining  term thereof or, if the Mortgage Loan provided that
the  amortization  period on which the Monthly  Payments were based was a longer
period, such period has not been extended, (D) the interest rate on the Mortgage
Loan will not be altered nor will the term of the Mortgage  Loan be increased as
a result of such assumption or transfer and (E) if the  seller/transferor of the
Mortgaged  Property is to be released from  liability on the Mortgage  Loan, the
Servicer used the same underwriting standards in evaluating the creditworthiness
of the  purchaser/transferee  as were used in making the original Mortgage Loan,
and such release  will not (based on the  Servicer's  good faith  determination)
adversely affect the  collectibility  of the Mortgage Loan. Upon receipt of such
certificate, the Trustee for the benefit of the Certificateholders shall execute
any necessary instruments for such assumption or substitution of liability. Upon
the closing of the  transactions  contemplated by such  documents,  the Servicer
shall cause the originals of the assumption agreement,  the release (if any), or
the  modification or supplement to the Mortgage Note or Mortgage to be delivered
to the  Trustee  or its  agent for the  benefit  of the  Certificateholders  and
deposited  with  the  Trustee  Mortgage  File for such  Mortgage  Loan.  Any fee
collected by the Servicer for entering  into an assumption  or  substitution  of
liability  agreement  will be retained by the Servicer as  additional  servicing
compensation.
          In the event that the Servicer, in connection with any such assumption
or  modification  agreement or  supplement  to the Mortgage  Note,  is unable to
deliver the certificate of the Servicing  Officer set forth above,  the Servicer
shall  purchase,  or cause the  related  Sub-Servicer  to  purchase  the related
Mortgage  Loan in the manner,  and at the Purchase  Price,  set forth in Section
2.04 hereof.
     SECTION 3.13 REALIZATION UPON DEFAULTED MORTGAGE LOANS.
          The Servicer shall foreclose upon or otherwise  comparably convert the
ownership of  properties  securing  such of the Mortgage  Loans as come into and
continue in default and as to which, in the reasonable judgment of the Servicer,
no satisfactory  arrangements can, in accordance with prudent lending practices,
be made for collection of delinquent  payments  pursuant to Section 3.01 hereof.
In connection  with such  foreclosure  or other  conversion,  the Servicer shall
follow such practices and procedures as it shall deem necessary or advisable, as
shall be normal and usual in its general mortgage  servicing  activities and for
its own portfolio and as are in accordance with the  requirements of the insurer
under  any  Required  Insurance  Policy  and  shall  deliver  to the  Trustee  a
liquidation  report  with  respect to the related  Mortgage  Loan on the form of
report customarily  prepared by the Servicer.  In particular,  the Servicer will
service  each  Mortgage  Loan in a manner  that  preserves  the right to proceed
against all collateral securing such Mortgage Loan (e.g., in accordance with any
applicable  "single action" rule).  The Servicer shall not be required to expend
its own funds in connection  with any  foreclosure  or towards the  restoration,
repair,  protection or maintenance of any property  unless it shall determine in
its sole  discretion that such expenses will be recoverable to it as Liquidation
Expenses either through  Liquidation  Proceeds  (respecting  which it shall have
priority for purposes of  withdrawals  from the  Custodial  Account  pursuant to
Section 3.09 hereof) or through  Insurance  Proceeds  (respecting which it shall
have similar  priority).  The Servicer shall be responsible  for all other costs
and expenses incurred by it in any such proceedings;  PROVIDED, HOWEVER, that it
shall be entitled to  reimbursement  thereof from the proceeds of liquidation of
the related Mortgaged Property, as contemplated in Section 3.09 hereof.
                                      -62-
          In the event that any Mortgaged Property becomes an REO Property,  the
deed or  certificate  of sale shall be taken in the name of the  Trustee for the
benefit  of  the   Certificateholders,   or  its  nominee,   on  behalf  of  the
Certificateholders.  Pursuant  to its  efforts  to sell such REO  Property,  the
Servicer  shall  either  itself or through  an agent  selected  by the  Servicer
protect and conserve  such REO Property in the same manner and to such extent as
is  customary  in the  locality  where such REO  Property  is  located  and may,
incident  to  its   conservation   and   protection  of  the  interests  of  the
Certificateholders, rent the same, or any part thereof, as the Servicer deems to
be in the best  interest  of the  Servicer  and the  Certificateholders  for the
period prior to the sale of such REO Property on such terms and  conditions  and
for  such  periods  as the  Servicer  deems to be in the  best  interest  of the
Servicer  and the  Certificateholders.  Notwithstanding  anything  herein to the
contrary,  in the event that the Trust  REMIC,  REMIC I or REMIC II acquires any
REO Property as aforesaid or otherwise in connection  with a default or imminent
default on a Mortgage Loan, the Servicer,  on behalf of the Trust REMIC, REMIC I
or REMIC II, shall dispose of such REO Property as soon as  practicable,  and in
any event within three full years after the taxable year of its  acquisition  by
the Trust REMIC,  REMIC I or REMIC II for purposes of Section  860G(a)(8) of the
Code  (or  such  shorter  period  as may be  necessary  under  applicable  state
(including  any state in which such  property  is located)  law to maintain  the
status of the Trust REMIC, REMIC I or REMIC II as a REMIC under applicable state
law and avoid  taxes  resulting  from such  property  failing to be  foreclosure
property  under  applicable  state law) or, at the  expense of the Trust  REMIC,
REMIC I or REMIC II,  request,  more than 60 days  before  the day on which such
grace period would  otherwise  expire,  an extension of such grace period unless
the  Servicer  obtains for the Trustee an Opinion of Counsel,  addressed  to the
Trustee and the  Servicer,  to the effect  that the holding by the Trust  REMIC,
REMIC I or REMIC II of such REO  Property  subsequent  to such  period  will not
result in the  imposition of taxes on  "prohibited  transactions"  as defined in
Section 860F of the Code, or cause the Trust REMIC,  REMIC I or REMIC II to fail
to  qualify  as a REMIC  under  the Code at any time that any  Certificates  are
outstanding,  in which case the Trust REMIC, REMIC I or REMIC II may continue to
hold such REO Property  (subject to any conditions  contained in such Opinion of
Counsel).  The Servicer  shall be entitled to be  reimbursed  from the Custodial
Account  for  any  costs   incurred  in  obtaining   such  Opinion  of  Counsel.
Notwithstanding any other provision of this Agreement,  no REO Property acquired
by the Trust REMIC,  REMIC I or REMIC II shall be rented (or allowed to continue
to be rented) or otherwise  used by or on behalf of the Trust REMIC,  REMIC I or
REMIC II in such circumstances or manner or pursuant to any terms that would (i)
cause such REO Property to fail to qualify as "foreclosure  property" within the
meaning of Section 860G(a)(8) of the Code or (ii) subject the Trust REMIC, REMIC
I or REMIC II to the imposition of any federal income taxes on the income earned
from such REO Property, including any taxes imposed by reason of Section 860G(c)
of the Code,  unless the Servicer has agreed to indemnify  and hold harmless the
Trust  REMIC,  REMIC I or REMIC II with  respect to the  imposition  of any such
taxes.
          The decision of the Servicer to foreclose on a defaulted Mortgage Loan
shall be subject to a  determination  by the Servicer  that the proceeds of such
foreclosure  would exceed the costs and expenses of bringing  such a proceeding.
The income  earned from the  management  of any  Mortgaged  Properties  acquired
through   foreclosure   or  other   judicial   proceeding   on   behalf  of  the
Certificateholders,  net of reimbursement to the Servicer for expenses  incurred
(including any taxes) in connection with such  management,  advances made by the
Servicer  pursuant to Sections 3.01,  3.08,  3.10,  3.11,  3.13, 5.01 or 5.02 in
connection  with the  related  Mortgage  Loan or REO  Property  and  Liquidation
Expenses  incurred by the Servicer in connection with the related Mortgage Loan,
shall be applied to the  payment of  principal  of and  interest  on the related
defaulted Mortgage Loans
                                      -63-
(with interest  accruing and principal  amortizing as though such Mortgage Loans
were still  current)  and all such income  shall be deemed,  for all purposes in
this  Agreement,  to be payments on account of  principal of and interest on the
related Mortgage Notes and shall be deposited into the Custodial Account.
          Prior to obtaining or causing the Trustee to obtain a deed as a result
of or in lieu of foreclosure,  or otherwise acquiring (or causing the Trustee to
acquire)  possession  of or title to any  Mortgaged  Property,  if the  Servicer
determines  that obtaining a deed or otherwise  acquiring title or possession of
such Mortgaged  Property  would likely subject the Servicer,  the Trustee or the
Trust Fund to  substantial  liability  in respect  of  environmental  conditions
concerning the Mortgaged Property, (a) the Servicer shall (i) notify the Trustee
and the  Depositor of such  determination  and (ii)  refrain  from  obtaining or
directing the Trustee to obtain a deed as a result of or in lieu of  foreclosure
or otherwise  acquiring  title or possession to such Mortgaged  Property and (b)
the obligations of the Servicer to make advances, including, without limitation,
Monthly  Advances,  in connection with the Mortgage Loan in question shall cease
as of the date that the Servicer makes such determination.
     SECTION 3.14 TRUSTEE TO COOPERATE; RELEASE OF TRUSTEE MORTGAGE FILES.
          Upon the payment in full of any Mortgage  Loan,  or the receipt by the
Servicer  of a  notification  that  payment in full will be escrowed in a manner
customary for such purposes,  and upon  notification by the Servicer in the form
of a certification  (which certification shall include a statement to the effect
that all amounts  received or to be received  in  connection  with such  payment
which are required to be deposited in the Custodial Account have been or will be
so  deposited)  of a Servicing  Officer and a Request for Release of the Trustee
Mortgage File in the form of Exhibit E hereto the Trustee shall promptly release
the related Trustee Mortgage File to the Servicer, and the Trustee shall execute
and deliver to the Servicer the request for  reconveyance,  deed of reconveyance
or release,  satisfaction or assignment of mortgage or such instrument releasing
the lien of the Mortgage, and, in each case, such other documents or instruments
as may be  reasonably  required  in  connection  therewith,  as  directed by the
Servicer,  together with the Mortgage Note with written evidence of cancellation
thereon. The provisions of the immediately  preceding sentence shall not, in any
manner,  limit or impair the right of the  Servicer to execute and  deliver,  on
behalf  of the  Trustee,  the  Certificateholders  or any of  them,  any and all
instruments of satisfaction,  cancellation or assignment,  or of partial or full
release or discharge and all other comparable  instruments,  with respect to the
Mortgage  Loans,  and with  respect  to the  Mortgaged  Properties  held for the
benefit of the  Certificateholders.  No expenses incurred in connection with any
instrument of satisfaction  or deed of  reconveyance  shall be chargeable to the
Certificate Account but shall be paid by the Servicer.  From time to time and as
shall be  appropriate  for the servicing or  foreclosure  of any Mortgage  Loan,
including,  without limitation, for such purpose, collection under any policy of
flood  insurance,  any fidelity bond or errors or omissions  policy,  or for the
purposes of effecting a partial or total release of any Mortgaged  Property from
the lien of the Mortgage or the making of any  corrections  to the Mortgage Note
or the Mortgage or any of the other documents  included in the Trustee  Mortgage
File,  the Trustee  shall,  upon request of the Servicer and the delivery to the
Trustee of a Request for Release signed by a Servicing  Officer,  in the form of
Exhibit E hereto,  release the Trustee  Mortgage  File to the  Servicer.  If the
Servicer at any time seeks to initiate a  foreclosure  proceeding  in respect of
any Mortgaged Property, the Servicer shall deliver to the Trustee, for signature
as  appropriate,  any court  pleadings,  requests  for  trustee's  sale or other
documents  necessary to effectuate such  foreclosure or any legal action brought
to obtain judgment against the
                                      -64-
Mortgagor  on the  Mortgage  Note or the  Mortgage  or to  obtain  a  deficiency
judgment or to enforce any other  remedies  or rights  provided by the  Mortgage
Note or the Mortgage or otherwise available at law or in equity, together with a
certificate of a Servicing  Officer  requesting that such pleadings or documents
be executed by the Trustee.  A Servicing  Officer shall certify as to the reason
such  documents or pleadings  are required and that the  execution  and delivery
thereof by the Trustee will not  invalidate  the  insurance  coverage  under any
Required  Insurance  Policy or  invalidate  or otherwise  affect the lien of the
Mortgage  except  for  the  termination  of such  lien  upon  completion  of the
foreclosure.
     SECTION 3.15  DOCUMENTS,  RECORDS AND FUNDS IN POSSESSION OF SERVICER TO BE
HELD FOR THE TRUSTEE FOR THE BENEFIT OF THE CERTIFICATEHOLDERS.
          Notwithstanding  any other provisions of this Agreement,  the Servicer
shall  transmit to the  Trustee to the extent  required  by this  Agreement  all
documents and  instruments  coming into the possession of the Servicer from time
to  time  and  shall  account  fully  to the  Trustee  for  the  benefit  of the
Certificateholders for any funds received by the Servicer or which otherwise are
collected  by the  Servicer as  Liquidation  Proceeds or  Insurance  Proceeds in
respect of any Mortgage  Loan. All Servicer  Mortgage Files or Trustee  Mortgage
Files and funds  collected  or held by, or under the control of, the Servicer in
respect of any Mortgage  Loans,  whether from the  collection  of principal  and
interest payments or from Liquidation Proceeds or Insurance Proceeds,  including
but not limited to, any funds on deposit in the Custodial Account, shall be held
by the  Servicer  for  and on  behalf  of the  Trustee  for the  benefit  of the
Certificateholders  and shall be and remain the sole and  exclusive  property of
the  Trustee,  subject  to the  applicable  provisions  of this  Agreement.  The
Servicer  also agrees that it shall not  create,  incur or subject any  Servicer
Mortgage  File or Trustee  Mortgage  File or any funds that are deposited in the
Custodial  Account  or any  Servicing  or  Escrow  Account,  or any  funds  that
otherwise are or may become due or payable to the Trustee for the benefit of the
Certificateholders,  to any claim, lien, security interest, judgment, levy, writ
of attachment or other  encumbrance,  or assert by legal action or otherwise any
claim or right of setoff against any Servicer  Mortgage File or Trustee Mortgage
File or any funds collected on, or in connection with, a Mortgage Loan,  except,
however,  that the Servicer shall be entitled to set off against and deduct from
any such funds any amounts  that are  properly  due and payable to the  Servicer
under this Agreement subject to the terms of this Agreement.
     SECTION 3.16 SERVICING COMPENSATION; COMPENSATING INTEREST.
          As compensation  for its activities  hereunder,  the Servicer shall be
entitled to (a) retain  from the Monthly  Payments  the  Servicing  Fee for each
Mortgage Loan and the Additional Servicing Fee for each Class AR5 Mortgage Loan,
and (b) retain from the Custodial Account or withdraw from the Custodial Account
the amounts  specified in subclause (a) of Section 3.09 hereof as payable to it.
Notwithstanding the foregoing, the Additional Servicing Fee may only be retained
from the Class AR5 Mortgage Loans.
          Additional servicing compensation in the form of prepayment penalties,
fees or premiums,  assumption fees,  modification  fees, late payment charges or
otherwise or any excess  interest  charges payable by the Mortgagor by virtue of
any  default  or other  non-compliance  by the  Mortgagor  with the terms of the
Mortgage or any other instrument or document executed in connection therewith or
otherwise  shall be  retained by the  Servicer to the extent not  required to be
deposited in the  Custodial  Account  pursuant to Section  3.07  hereof.  To the
extent provided in this
                                      -65-
Agreement,  the Servicer shall be required to pay all expenses incurred by it in
connection  with its servicing  activities  hereunder  (including the payment of
premiums for Primary Mortgage  Insurance  Policies,  to the extent such premiums
are not  required to be paid or have not been paid by the related  Mortgagor  or
the related  Sub-Servicer,  payment of any  premiums  for hazard  insurance,  as
required by Section 3.11 hereof and  maintenance of the other forms of insurance
coverage required by Section 3.11 hereof, the payment of servicing  compensation
to any Sub-Servicers pursuant to any Sub-Servicing  Agreement and the payment of
the expenses of the Trustee to the extent  provided in Section 9.05),  and shall
not be entitled to  reimbursement  therefor except as  specifically  provided in
Sections 3.09, 3.13, 4.01 and 5.03 hereof.
          Notwithstanding  any other provision  herein,  the amount of servicing
compensation  that the Servicer  shall be entitled to receive for its activities
hereunder for the period ending on each  Distribution Date shall be reduced (but
not below zero) by an amount  equal to  Compensating  Interest (if any) for such
Distribution  Date.  The  Servicer  shall,  within  one  Business  Day  of  each
Distribution  Date, remit to the Trustee the  Compensating  Interest due on such
Distribution  Date.  In the event that more than one Loan Group is  entitled  to
Compensating  Interest and the amount of the aggregate  Compensating Interest is
less than interest that should have been  remitted on Principal  Prepayments  in
Full by Mortgagors  during the related Due Period,  such  Compensating  Interest
shall be distributed pro rata among each Loan Group.
     SECTION 3.17 REPORTS TO THE DEPOSITOR; ACCOUNT STATEMENTS.
          Within five  Business  Days  following  each  Distribution  Date,  the
Servicer  shall  deliver to the Trustee a statement  setting forth the status of
the Custodial Account,  if any, as of the close of business on such Distribution
Date  showing,  for the  period  covered by such  statement,  the  aggregate  of
deposits in or withdrawals from the Custodial Account, if any, for each category
of deposit  specified  in Section  3.07 hereof and each  category of  withdrawal
specified in Section 3.09 hereof.
          As long as the Class I-A Certificates and the Class B Certificates are
outstanding,  the Servicer  shall forward a copy of such statement to the Rating
Agencies.
     SECTION 3.18 ANNUAL STATEMENT AS TO COMPLIANCE.
          The  Servicer  shall  deliver to the  Depositor  and the Trustee on or
before  March  31  of  each  year,  commencing  March  31,  2001,  an  Officers'
Certificate  stating,  as to each  signer  thereof,  that  (a) a  review  of the
activities of the Servicer  during the year ended on the  preceding  December 31
and of the  performance of the Servicer under this Agreement has been made under
such officer's supervision,  (b) to the best of such officer's knowledge,  based
on such review,  the  Servicer  has  fulfilled  all its  obligations  under this
Agreement in all material respects throughout such year, or, if there has been a
default in the fulfillment of any such obligation,  specifying each such default
known to such officer and the nature and status thereof, (c) a Servicing Officer
has conducted an examination of the activities of each  Sub-Servicer  during the
immediately   preceding  year  and  its  performance   under  any  Sub-Servicing
Agreement,  and (d) to the best of such Servicing Officer's knowledge,  based on
such  examination,  each  Sub-Servicer  has  performed and fulfilled its duties,
responsibilities  and  obligations  under such  Sub-Servicing  Agreement  in all
material  respects  throughout  such year, or if there has been a default in the
performance or fulfillment of any such
                                      -66-
duties,  responsibilities or obligations,  specifying each such default known to
such Servicing Officer and the nature and status thereof.
          As long as the Class I-A Certificates and the Class B Certificates are
outstanding,  the Servicer  shall forward a copy of such statement to the Rating
Agencies.
     SECTION 3.19 ANNUAL INDEPENDENT PUBLIC ACCOUNTANTS' SERVICING REPORT.
          On or before March 31 of each year,  beginning with the first March 31
that occurs at least eleven months after the Cut-off Date, the Servicer,  at its
expense,  shall cause a firm of independent  public accountants that is a member
of the American Institute of Certified Public Accountants to furnish a statement
to the  Depositor and the Trustee for the benefit of the  Certificateholders  to
the effect that such firm has examined certain documents  substantially  similar
to this  Agreement  and records  relating  to the  servicing  of mortgage  loans
serviced  by the  Servicer  or any  successor  servicer  that are  substantially
similar to the Mortgage Loans and that, on the basis of an examination conducted
substantially  in compliance  with the Uniform Single Audit Program for Mortgage
Bankers or the Audit  Program  for  Mortgages  serviced  for Freddie  Mac,  such
servicing has been conducted in compliance with such agreements  except for such
significant  exceptions  or errors in records that, in the opinion of such firm,
the Uniform  Single Audit Program for Mortgage  Bankers or the Audit Program for
Mortgages  serviced  for Freddie Mac requires it to report.  In  rendering  such
statement  such firm may rely,  as to matters  relating to direct  servicing  of
Mortgage  Loans  by  Sub-Servicers,  if  any,  upon  comparable  statements  for
examinations conducted substantially in compliance with the Uniform Single Audit
Program for Mortgage  Bankers or the Audit  Program for  Mortgages  serviced for
Freddie Mac (rendered  within one year of such statement) of independent  public
accounts with respect to the related Sub-Servicer.
          As long as the Class I-A Certificates and the Class B Certificates are
outstanding,  the Servicer  shall forward a copy of such statement to the Rating
Agencies.
     SECTION 3.20 REPORTS TO TRUSTEE.
          On or prior to each Determination Date, the Servicer shall cause to be
delivered  to the  Trustee  a monthly  servicing  report  in  electronic  format
containing  the  information  necessary  to  enable  the  Trustee  to  make  the
distribution  required by Section 4.02 and prepare the  information set forth in
Section 4.04(a).  The Trustee may conclusively  rely on information  provided by
the Servicer and shall have no obligation to recompute,  recalculate,  or verify
the accuracy of such information.
                                   ARTICLE IV
                  PAYMENTS AND STATEMENTS TO CERTIFICATEHOLDERS
     SECTION 4.01 CERTIFICATE ACCOUNT.
          The Trustee shall  establish,  prior to the Delivery  Date,  and shall
maintain,  in the name of the Trustee on behalf of the Holders of  interests  in
the Trust Fund, the  Certificate  Account,  which shall be an Eligible  Account,
into which the Trustee upon receipt from the Servicer shall deposit all payments
remitted  by the  Servicer  and  any  amounts  required  to be  remitted  by the
Depositor  pursuant to the terms hereof.  All distributions to be made from time
to  time  to  Holders  of  interests  in the  Trust  Fund  out of  funds  in the
Certificate  Account  shall be made by or on behalf
                                      -67-
of the Trustee. The Trustee will give notice to the Servicer, the Depositor and,
so long as any Class  I-A or Class B  Certificate  is  outstanding,  the  Rating
Agencies,  of the location of the Certificate Account and of any change thereof,
prior to the use thereof. Funds held in the Certificate Account and delivered to
the Trustee  earlier than one Business Day prior to the next  Distribution  Date
shall be  invested by the  Trustee in  Eligible  Investments  as directed by the
Servicer or shall remain uninvested.  The Trustee shall cause each such Eligible
Investment  to be  Delivered  to it  or  its  nominee  (including  a  securities
intermediary).  All  income and gain net of any  losses  realized  from any such
investment  shall be for the  benefit  of the  Servicer  and shall be subject to
withdrawal  at the  Servicer's  direction  from time to time.  The amount of any
losses  net of any  gains  incurred  by the  Servicer  in  respect  of any  such
investments shall be deposited in the Certificate  Account out of the Servicer's
own funds immediately as realized.  Funds on deposit in the Certificate  Account
on the Business Day prior to the next Distribution Date shall be uninvested.
          The  Trustee  shall  make,  to  the  extent   required  or  authorized
hereunder, withdrawals from the Certificate Account for the following purposes:
               (i) to withdraw any amount  deposited in the Certificate  Account
and not required to be deposited therein;
               (ii)   to   reimburse   the   Servicer   for   any   unreimbursed
Nonrecoverable  Advance,  PROVIDED,  HOWEVER,  that reimbursements in respect of
Mortgage  Loans in Loan  Group 5, Loan  Group 6, Loan  Group 7, Loan Group 8 and
Loan Group 9 as a group and the Class Y Mortgage Loans may only  reimbursed from
aggregate  amounts  collected with respect to Mortgage Loans in such Loan Groups
or with respect to the Class Y Mortgage Loans, respectively,  and reimbursements
in  respect  of Class  AR5  Mortgage  Loans  may only  reimbursed  from  amounts
collected on the Class AR5 Mortgage Loans;
               (iii) to make  required  distributions  pursuant to Section 4.02;
and
               (iv) to pay to the  Depositor or the Servicer any amount to which
it is entitled pursuant to Section 7.03.
     SECTION 4.02 DISTRIBUTIONS.
          (a) On each  Distribution  Date,  the Trustee shall  withdraw from the
Certificate Account:
     (x) an amount  equal to the  Available  Distribution  Amount  for each Loan
Group and pay such amount in the following order of priority:
               (i) to the  holders  of the  Class  A  Certificates  or  Class  R
Certificates in such Loan Group the related Class A Interest Distribution Amount
and the  Class A  Cumulative  Interest  Shortfall  Amount  or  Class R  Interest
Distribution Amount, as applicable;  provided that if the Available Distribution
Amount is insufficient to make the full distributions of interest referred to in
this clause,  the Available  Distribution  Amount shall be  distributed  to such
Class A Certificates pro rata based on such full amounts allocable to such Class
and  provided  further  that with  respect to Loan Group 9 such amount  shall be
first paid to the holders of the Class R Certificates  in respect of the Class R
Interest Distribution Amount;
                                      -68-
               (ii) to the Class A  Certificates  in such Loan Group  (or,  with
respect  to  Loan  Group  9,  the  Class  R   Certificateholders   and  Class  A
Certificateholders in such Loan Group) until the aggregate Certificate Principal
Balance of the Class A Certificates (or, with respect to Loan Group 9, the Class
R  Certificateholders  and Class A  Certificateholders  in such Loan Group) have
been reduced to zero (applied to reduce the Certificate Principal Balance of the
Class A Certificates or Class R Certificates, as applicable) the related Class A
Principal  Distribution  Amount or Class R  Principal  Distribution  Amount,  as
applicable; and
               (iii) to the Class R  Certificates,  the balance,  if any, of the
Available Distribution Amount.
     (y) On each Distribution  Date for the Class AR5 Certificates,  the Class Y
Distribution  Amount  shall  be  distributed  to  the  holder  of  the  Class  Y
Certificates.
     (z) the Trustee shall  distribute  the Available  Distribution  Amount with
respect to the Class AR5 Certificates on each  Distribution  Date to the Holders
of the Class AR5 Certificates in the following order of priority:
          (i) first, to the holders of the Class I-R  Certificates in respect of
     the Class R-II Component,  the Class R-I Interest  Distribution Amount, and
     then to the holders of the Class I-A  Certificates,  the Class I-A Interest
     Distribution Amount and any Class I-A Cumulative Interest Shortfall Amount;
          (ii) second,  to the holders of the Class I-R  Certificates in respect
     of Class R-II Component, the Senior Principal Distribution Amount until the
     respective Certificate Principal Balances thereof have been reduced to zero
     and then to the holders of the Class I-A Certificates, the Senior Principal
     Distribution Amount;
          (iii)third,  to the holders of Class B-1  Certificates,  the Class B-1
     Interest   Distribution  Amount  and  any  Class  B-1  Cumulative  Interest
     Shortfall Amount;
          (iv) fourth, to the Holders of the Class B-1 Certificates, the portion
     of the Subordinate Principal Distribution Amount distributable to the Class
     B-1 Certificates;
          (v) fifth,  to the  holders of Class B-2  Certificates,  the Class B-2
     Interest   Distribution  Amount  and  any  Class  B-2  Cumulative  Interest
     Shortfall Amount;
          (vi) sixth, to the Holders of the Class B-2 Certificates,  the portion
     of the Subordinate Principal Distribution Amount distributable to the Class
     B-2 Certificates;
          (vii) seventh, to the holders of Class B-3 Certificates, the Class B-3
     Interest   Distribution  Amount  and  any  Class  B-3  Cumulative  Interest
     Shortfall Amount;
          (viii)  eighth,  to the  Holders  of the Class B-3  Certificates,  the
     portion of the Subordinate  Principal  Distribution Amount distributable to
     the Class B-3 Certificates;
          (ix) ninth,  to the holders of Class B-4  Certificates,  the Class B-4
     Interest   Distribution  Amount  and  any  Class  B-4  Cumulative  Interest
     Shortfall Amount;
                                      -69-
          (x) tenth, to the Holders of the Class B-4  Certificates,  the portion
     of the Subordinate Principal Distribution Amount distributable to the Class
     B-4 Certificates;
          (xi) eleventh, to the holders of Class B-5 Certificates, the Class B-5
     Interest   Distribution  Amount  and  any  Class  B-5  Cumulative  Interest
     Shortfall Amount;
          (xii)  twelfth,  to the  Holders  of the Class B-5  Certificates,  the
     portion of the Subordinate  Principal  Distribution Amount distributable to
     the Class B-5 Certificates;
          (xiii) thirteenth, to the holders of Class B-6 Certificates, the Class
     B-6  Interest  Distribution  Amount and any Class B-6  Cumulative  Interest
     Shortfall Amount;
          (xiv) fourteenth,  to the Holders of the Class B-6  Certificates,  the
     portion of the Subordinate  Principal  Distribution Amount distributable to
     the Class B-6 Certificates; and
          (xv) fifteenth,  any remaining amounts to the holders of the Class I-R
     Certificates in respect of the Class R-I Component.
          (b) The Trustee shall be responsible for the calculations with respect
to distributions from the Certificate  Account so long as the Trust Fund has not
been  terminated in accordance with this Agreement.  All  distributions  made to
Certificateholders  of any Class on such  Distribution  Date will be made to the
Certificateholders  of  the  respective  Class  of  record  on  the  immediately
preceding Record Date, except for the final distribution, which shall be made as
provided  in  the  form  of   Certificate.   All   distributions   made  to  the
Certificateholders  shall be based upon the Percentage  Interest  represented by
their  respective  Certificates.  If on  any  Determination  Date,  the  Trustee
determines  that there are no Mortgage Loans  outstanding  and no other funds or
assets in the Trust Fund other than the funds in the  Certificate  Account,  the
Trustee   shall   promptly   send  the   final   distribution   notice  to  each
Certificateholder  specifying the manner in which the final distribution will be
made.
          (c) Any  Certificateholder  shall be entitled to receive distributions
hereunder  on a  Distribution  Date (other  than as  provided  in Section  10.02
respecting the final  distribution) by wire transfer to the account specified in
writing  by the  Certificateholder  to the  Trustee if the  Initial  Certificate
Principal  Balance  evidenced by such Holder's  Certificate is at least equal to
$2,500,000 or the Percentage Interest thereof is 100%; provided,  however,  that
any distribution in respect of any Certificate that is held by the Seller or the
Servicer  (regardless  of  Initial  Certificate  Balance)  shall be paid by wire
transfer if the Seller or Servicer, as applicable,  has provided to the Trustee,
in writing,  the account for such wire transfer.  In each case, the account must
be specified in writing at least five Business Days prior to the Record Date for
the Distribution Date, as applicable, on which wire transfers will commence. All
other  distributions  shall be made by check  payable  to the  Certificateholder
mailed by first class mail to the address of such Certificateholder reflected in
the Certificate Register.
     SECTION 4.03 ALLOCATION OF REALIZED LOSSES.
          Prior to each Distribution Date, based on the information  provided by
the Servicer in its monthly  report,  the Trustee  shall  determine the total of
Realized  Losses,  if any,  incurred with respect to the Mortgage  Loans in each
Loan Group during the previous  Prepayment  Period. On each  Distribution  Date,
Realized  Losses will be  allocated  after the  distribution  of  principal
                                      -70-
and  interest  on  such  Distribution  Date;  PROVIDED,  HOWEVER,  that  if  the
Certificate  Principal Balance of any Class of Certificates  would be reduced to
zero as a result of Realized Losses to be allocated on such Distribution Date if
no funds were available for  distributions  on the  Certificates,  then Realized
Losses will be  allocated to such Class prior to the  distribution  of principal
and  interest.  In every  case,  each Loan  Group  and the Class A  Certificates
related thereto,  shall bear Realized Losses incurred in such Loan Group.  Class
AR5  Certificates  shall only bear Realized  Losses  allocated to the Class A-1,
Class A-2,  Class A-3 and Class A-4  Certificates  in  accordance  with the last
paragraph of this Section 4.03 on the related Distribution Date.
          Except as provided in the following  sentence,  any  allocation of the
principal portion of Realized Losses to a Class of Certificates shall be made by
reducing the Certificate  Principal  Balance thereof by the amount so allocated,
which  allocation  shall be deemed to have occurred on such  Distribution  Date.
Allocations  of the  interest  portions  of  Realized  Losses  shall  be made by
operation of the  provisions  of Section  4.02(a).  All Realized  Losses and all
other losses  allocated to a Class of  Certificates  hereunder will be allocated
among the  Certificates of such Class in proportion to the Percentage  Interests
evidenced thereby.
          The Class AR5 Certificates  shall bear only the Realized Losses on the
Class AR5  Mortgage  Loans.  Except for Special  Hazard  Losses in excess of the
Special  Hazard  Coverage,  Fraud  Losses in excess  of the Fraud  Coverage  and
Bankruptcy Losses in excess of the Bankruptcy  Coverage,  Realized Losses on the
Class AR5 Mortgage Loans shall be allocated  (without  duplication) first to the
Class B-6 Certificates until the Certificate  Principal Balance thereof has been
reduced  to zero,  then to the Class  B-5  Certificates  until  the  Certificate
Principal  Balance  thereof  has been  reduced  to zero,  then to the  Class B-4
Certificates until the Certificate Principal Balance thereof has been reduced to
zero, then to the Class B-3 Certificates until the Certificate Principal Balance
thereof has been reduced to zero, then to the Class B-2  Certificates  until the
Certificate  Principal  Balance  thereof has been  reduced to zero,  then to the
Class B-1 Certificates until the Certificate  Principal Balance thereof has been
reduced to zero, then to the Class I-A Certificates. All Realized Losses and all
other losses  allocated to a Class of Class AR5  Certificates  hereunder will be
allocated  among the  Certificates of such Class in proportion to the Percentage
Interests  evidenced  thereby.  Special  Hazard  Losses in excess of the Special
Hazard  Coverage,  Fraud Losses in excess of the Fraud  Coverage and  Bankruptcy
Losses in excess of the Bankruptcy  Coverage shall be allocated  among the Class
AR5 Certificates by Pro Rata Allocation.
     SECTION 4.04 MONTHLY STATEMENTS TO CERTIFICATEHOLDERS.
          (a) Not later than each  Distribution  Date, the Trustee shall prepare
and the Trustee  shall cause to be forwarded by mail to each  Certificateholder,
the Servicer,  the  Depositor,  and, as long as the Class AR5  Certificates  are
outstanding, to the Rating Agencies and Bloomberg, a statement setting forth the
following information as to each Class of Certificates to the extent applicable:
               (i) the  amount  of  such  distribution  representing  principal,
separately  identifying  (1) the aggregate  amount of any Principal  Prepayments
included therein, (2) the portion of such distribution,  if any,  representing a
Monthly  Advance  of  principal,  and (3) the  aggregate  Certificate  Principal
Balance of each Class  Certificates,  after giving effect to such distributions,
separately  identifying any reduction  thereof due to Realized Losses other than
pursuant to an actual distribution of principal;
                                      -71-
               (ii) the amount of such  distribution  representing  interest and
the portion of such  distribution,  if any,  representing  a Monthly  Advance of
interest;
               (iii) the aggregate  Principal  Balances of the Mortgage Loans as
of the close of business on such  Distribution  Date and the amount of Principal
Prepayments  and  the  aggregate   Principal  Balances  of  the  Mortgage  Loans
repurchased by the Seller during the immediately preceding Prepayment Periods;
               (iv)  the  Servicing  Fees  and  Additional  Servicing  Fees  (as
applicable) retained by the Servicer;
               (v)  the  amount  of  Monthly  Advances  paid  by  the  Servicer,
segregating such Monthly  Advances  relating to Loan Group 5, Loan Group 6, Loan
Group 7, Loan  Group 8, Loan  Group 9 and the Class Y  Mortgage  Loans,  and the
Monthly Advances relating to the Class AR5 Mortgage Loans;
               (vi) the number and aggregate principal amounts of Mortgage Loans
(A) delinquent (1) one month,  (2) two months,  (3) three months or more and (B)
in foreclosure and (C) in bankruptcy;
               (vii) the book value (within the meaning of 12 C.F.R.ss.571.13 or
comparable provision) of any REO Property;
               (viii)  the  respective  amounts,  if  any,  of  Realized  Losses
allocated  to the  respective  Classes  of  Certificates  with  respect  to such
Distribution Date;
               (ix) all Monthly Advances recovered during the related Due Period
and the extent of Monthly Advances remaining unreimbursed;
               (x) the amount of any tax imposed on a  "prohibited  transaction"
of the Trust Fund as defined in Section  860F of the Code during the related Due
Period;
               (xi)  the  amount  of  any  reduction  in  Certificate  Principal
Balance,  the Class A Cumulative Interest Shortfall Amount or Class A or Class R
Interest  Distribution  Amount for any Class  attributable to the application of
Realized Losses thereto on such Distribution Date;
               (xii) the Certificate Rate applicable for such  Distribution Date
and the Class AR5 Pass-Through Rate applicable for such Distribution Date;
               (xiii) the  aggregate  principal  balance of all  Mortgage  Loans
which are the subject of  substitution  or  purchase  by the Seller  pursuant to
Section 2.01.  2.02. 2.03, 2.04 or 3.12,  during the month of such  Distribution
Date,  together with the number of such Mortgage Loans removed and the amount of
any resulting  shortage  deposited  into the Custodial  Account by the Seller or
Servicer in such month;
               (xiv) the Class AR5 Distribution Amount;
               (xv) the Class Y Distribution Amount,  separating out such amount
allocable to principal and such amount allocable to interest;
                                      -72-
               (xvi) the Cumulative Interest Shortfall Amount for each Class, as
applicable; and
               (xvii) cumulative Realized Losses since the Delivery Date and for
the three year period commencing on the Delivery Date.
The foregoing information shall be provided by the Trustee to the holders of the
Class AR Certificates via the Trustee's internet website. The Trustee's internet
website shall initially be located at "▇▇▇.▇▇▇.▇▇▇▇▇▇▇.▇▇▇." Assistance in using
the website can be obtained by calling the  Trustee's  customer  service desk at
(▇▇▇) ▇▇▇-▇▇▇▇.  Parties that are unable to use the website are entitled to have
a paper copy mailed to them via first class mail by calling the customer service
desk and  indicating  such.  The Trustee  shall have the right to change the way
Distribution  Date  statements  are  distributed  to the holders of the Class AR
Certificates  in order to make such  distribution  more  convenient  and/or more
accessible  to the above  parties,  provided  that such  procedures  are no less
convenient  for the Class AR  Certificateholders,  and the Trustee shall provide
timely and adequate notification to all above parties regarding any such changes
          (b) Upon reasonable advance notice in writing,  if required by federal
regulation, the Trustee will provide to each Certificateholder that is a savings
association, bank or insurance company certain reports and access to information
and  documentation  regarding  the  Mortgage  Loans  sufficient  to permit  such
Certificateholder to comply with applicable  regulations of the Office of Thrift
Supervision or other  regulatory  authorities  with respect to investment in the
Certificates and the Servicer shall cooperate with the Trustee in providing such
information;  provided,  however,  that  the  Trustee  shall be  entitled  to be
reimbursed  by each such  Certificateholder  for the Trustee's  actual  expenses
incurred in providing  such reports and access.  The Trustee will provide to any
Certificateholder upon request the outstanding Certificate Principal Balances as
of the date  requested  and,  if then  known  by the  Trustee,  the  outstanding
Certificate  Principal  Balances after giving effect to any  distribution  to be
made on the next following Distribution Date.
     SECTION 4.05 PREPAYMENT INTEREST SHORTFALLS AND RELIEF ACT SHORTFALLS.
          Prepayment  Interest  Shortfalls  resulting  in any Loan  Group from a
Principal  Prepayment of a Mortgage Loan during any Prepayment Period and Relief
Act  Shortfalls  occurring  during the related  Interest  Accrual Period will be
applied to reduce the Interest  Distribution  Amount of the Class A Certificates
in such Loan Group. Prepayment Interest Shortfalls resulting with respect to the
Class  AR5  Mortgage  Loans  or the  Class Y  Mortgage  Loans  from a  Principal
Prepayment  of a  Mortgage  Loan  during  any  Prepayment  Period and Relief Act
Shortfalls occurring during the related Due Period will be applied to reduce the
Interest  Distribution  Amount of each Class of the Class AR5  Certificates  pro
rata based upon the amount of the Interest  Distribution  Amount that would have
been   distributed   to  such  Class  absent  such  reduction  or  the  Class  Y
Certificates, respectively.
                                      -73-
                                    ARTICLE V
                                    ADVANCES
     SECTION 5.01 MONTHLY ADVANCES BY THE SERVICER.
          Subject to the conditions of this Article V, the Servicer, as required
below, shall make a Monthly Advance to the Certificate  Account,  in the amount,
if any, of the aggregate  Monthly Payments less Prepayment  Interest  Shortfalls
and Relief Act Shortfalls, after adjustment of the interest portion of each such
Monthly  Payment to the Net  Mortgage  Rate or Class AR5 Net Mortgage  Rate,  as
applicable,  on the  Mortgage  Loans that were due on the Due Date but that were
not received and remitted to the Certificate Account on or prior to the Servicer
Advance Date. The Servicer  shall be obligated to make any such Monthly  Advance
only to the  extent  that  such  advance,  in the  good  faith  judgment  of the
Servicer, will not be a Nonrecoverable Advance. Monthly Advances with respect to
the  Mortgage  Loans in Loan  Group 5, Loan Group 6, Loan Group 7, Loan Group 8,
Loan Group 9 and the Class Y Mortgage Loans shall only be allocated to the Class
A-5,  Class A-6,  Class  A-7,  Class A-8,  Class A-9,  and Class Y  Certificates
collectively  and Monthly  Advances with respect to the Class AR5 Mortgage Loans
shall only be allocated to the Class AR5 Certificates.
          On  the   Determination   Date   immediately   preceding  the  related
Distribution  Date, the Servicer shall determine  whether and to what extent any
Mortgagor has failed to make any Monthly Payment due on the Due Date and whether
such  deficiencies,  if  advanced  by the  Servicer,  would be a  Nonrecoverable
Advance.  If the Servicer shall have determined that it is not obligated to make
the entire  Monthly  Advance  because  all or a lesser  portion of such  Monthly
Advance would not be recoverable by the Servicer from related Insurance Proceeds
or  Liquidation  Proceeds  (net of  Liquidation  Expenses),  the Servicer  shall
deliver to the  Trustee,  not less than two  Business  Days prior to the related
Distribution Date, for the benefit of the Certificateholders, a certificate of a
Servicing Officer setting forth the reasons for such determination.
          In lieu  of  making  all or a  portion  of any  Monthly  Advance,  the
Servicer may cause to be made an  appropriate  entry in its records  relating to
the Custodial  Account that funds in such account,  including but not limited to
any  amounts  received in respect of  scheduled  principal  and  interest on any
Mortgage  due  after  the  related  Due  Period,  in  excess  of  the  Available
Distribution  Amount (less the amount of such  Monthly  Advance) for the related
Distribution  Date have been used by the Servicer in discharge of its obligation
to make any such Monthly Advance.  Any funds so applied shall be replaced by the
Servicer by deposit,  in the manner set forth above, in the Custodial Account no
later than the Servicer  Advance Date to the extent that funds in the  Custodial
Account on such date are less than the amounts required to be distributed on the
related  Distribution Date. The Servicer shall be entitled to be reimbursed from
the Custodial  Account and the Certificate  Account for all Monthly  Advances of
its own funds made  pursuant to this  Section as  provided  in Section  3.09 and
4.01.
     SECTION 5.02 ADVANCES FOR ATTORNEYS' FEES.
          The Servicer shall make advances from time to time for attorneys' fees
and court costs  incurred,  or which  reasonably can be expected to be incurred,
for the  foreclosure  of any Mortgage Loan or for any  transaction  in which the
Trustee  for the  benefit of the  Certificateholders
                                      -74-
is expected to receive a deed-in-lieu  of  foreclosure,  unless the Servicer has
made a good  faith  determination  that such  advances  would be  Nonrecoverable
Advances.  If the  Servicer  shall  make a good  faith  determination  that such
advances would not be so recoverable, the Servicer shall promptly deliver to the
Trustee a Certificate of a Servicing  Officer setting forth the reasons for such
determination.  The  Servicer  shall be entitled to  reimbursement  for any such
advance as provided in Section 3.09 hereof.
     SECTION 5.03 NONRECOVERABLE ADVANCES.
          The  determination  by the Servicer that it has made a  Nonrecoverable
Advance  shall be evidenced by a  certificate  of a Servicing  Officer  promptly
delivered  to the Trustee  setting  forth the  reasons  for such  determination.
Following  the  Trustee's  receipt of such  certificate,  the Servicer  shall be
entitled to reimbursement for such Nonrecoverable Advance as provided in Section
3.09 and 4.01 hereof.
     SECTION 5.04 ADVANCE PROCEDURES.
          (a) If, on any Determination  Date, the Servicer  determines to make a
Monthly  Advance in  accordance  with Section  5.01,  it shall make such Monthly
Advance on or before  noon,  New York  time,  on the  Business  Day prior to the
related  Distribution  Date (the "Servicer  Advance  Date").  The Servicer shall
notify  the  Trustee  of  the  aggregate   amount  of  Monthly  Advances  for  a
Distribution  Date on or before three  Business Days prior to such  Distribution
Date. Any such Monthly  Advance shall be included with the  distribution  on the
related Distribution Date pursuant to Section 4.02.
          (b) In the event  that the  Servicer  fails to make a Monthly  Advance
required to be made pursuant to Section 5.01 on or before the close of business,
on the Servicer  Advance Date,  the Trustee shall on or before 12 noon, New York
time on the next Business Day provide  notice to the Servicer,  by telephone and
by writing  (which may be by  telecopy)  of such  failure and the amount of such
failure and that  continuance  of such  failure for a period of one Business Day
thereafter will be an Event of Default.
                                   ARTICLE VI
                                THE CERTIFICATES
     SECTION 6.01 THE CERTIFICATES.
          (a) The Certificates  shall be in substantially the forms set forth in
Exhibits  A  and  B  hereto,  with  such  appropriate   insertions,   omissions,
substitutions  and  other  variations  as are  required  or  permitted  by  this
Agreement or as may in the  reasonable  judgment of the Trustee or the Depositor
be necessary,  appropriate  or convenient to comply,  or facilitate  compliance,
with  applicable  laws,  and may have such  letters,  numbers or other  marks of
identification  and  such  legends  or  endorsements  placed  thereon  as may be
required to comply with the rules of any securities exchange on which any of the
Certificates may be listed, or as may,  consistently  herewith, be determined by
the officers  executing  such  Certificates,  as  evidenced  by their  execution
thereof.
          The   definitive   Certificates   shall   be   printed,   typewritten,
lithographed  or engraved or produced by any combination of these methods or may
be  produced  in any  other  manner  permitted
                                      -75-
by the rules of any securities  exchange on which any of the Certificates may be
listed,  all as  determined  by the officers  executing  such  Certificates,  as
evidenced by their execution thereof.
          Each of the Class A Certificates will be in fully-registered form only
in minimum  denominations of $100,000 Certificate Principal Balance and integral
multiples  of $1  in  excess  thereof.  Each  of  the  Class  R  and  Class  I-R
Certificates will be in fully-registered  form only in minimum  denominations of
20% percentage interest.
          The Class I-A, Class B-1, Class B-2 and Class B-3 Certificates will be
in minimum  denominations of $25,000 Certificate  Principal Balance and integral
multiples of $1 in excess  thereof.  Each of the Class B-4,  Class B-5 and Class
B-6  Certificates  will be in  minimum  denominations  of  $250,000  Certificate
Principal Balance and integral multiples of $1 in excess thereof.
          The Certificates shall be executed by manual or facsimile signature on
behalf of the Trust Fund by the Trustee by a Responsible  Officer.  Certificates
bearing the manual or facsimile  signatures of individuals who were, at the time
when such signatures  were affixed,  authorized to sign on behalf of the Trustee
shall bind the Trust Fund,  notwithstanding that such individuals or any of them
have ceased to be so authorized prior to the authentication and delivery of such
Certificates  or did not hold such offices at the date of such  Certificate.  No
Certificate  shall be entitled to any benefit under this Agreement,  or be valid
for any purpose,  unless there  appears on such  Certificate  a  certificate  of
authentication executed by the Trustee by manual signature, and such certificate
of  authentication  upon any Certificate shall be conclusive  evidence,  and the
only evidence,  that such Certificate has been duly  authenticated and delivered
hereunder. All Certificates shall be dated the date of their authentication.
          (b) From time to time Washington  Mutual, as the initial Holder of the
Class Y  Certificate,  may  exchange  such  Holder's  Class Y  Certificates  for
Subclasses  of  Class Y  Certificates  to be  issued  under  this  Agreement  by
delivering a "Request for Exchange" substantially in the form attached hereto as
Exhibit K executed by an authorized officer, which Subclasses, in the aggregate,
will  represent  the  REMIC  regular  interests  corresponding  to the  Class  Y
Certificates  so surrendered  for exchange.  Any Subclass so issued shall bear a
numerical  designation  commencing  with Class Y-1 and  continuing  sequentially
thereafter,  and will  evidence  ownership of the  uncertificated  REMIC regular
interest  or  interests  specified  in  writing  by such  initial  Holder to the
Trustee.  The Trustee may  conclusively,  without any independent  verification,
rely  on,  and  shall  be   protected   in  relying  on,   Washington   Mutual's
determinations  of  the  uncertificated  REMIC  interests  corresponding  to any
Subclass, the initial Certificate Principal Balance and the initial Pass-Through
Rate on a Subclass  as set forth in such  Request for  Exchange  and the Trustee
shall have no duty to determine if any  uncertificated  REMIC regular  interests
designated  on a  Request  for  Exchange  corresponds  to a  Subclass  which has
previously been issued. The Class Y Distribution  Amount for each subclass shall
be the  portion  of the  Class Y  Distribution  Amount  related  to the  Class Y
Mortgage  Loans  representing  such  subclass.  Each Subclass so issued shall be
substantially  in the form set forth in Exhibit K and shall,  on original issue,
be executed  and  delivered  by the  Trustee to the  Certificate  Registrar  for
authentication   and  delivery  in  accordance  with  Section   6.01(a).   Every
Certificate  presented or  surrendered  for exchange by the initial Holder shall
(if so required by the Trustee or the  Certificate  Registrar)  be duly endorsed
by, or be  accompanied  by a written  instrument  of  transfer  attached to such
Certificate  and shall be completed to the  satisfaction  of the Trustee and the
Certificate  Registrar  duly  executed  by, the  initial  Holder  thereof or his
attorney duly authorized in
                                      -76-
writing.  The  Certificates  of any  Subclass  of  Class Y  Certificates  may be
transferred  in whole,  but not in part,  in accordance  with the  provisions of
Section 6.02.
     SECTION 6.02 REGISTRATION OF TRANSFER AND EXCHANGE OF CERTIFICATES.
          (a)  The  Trustee  shall  maintain,  or  cause  to  be  maintained,  a
Certificate Register in which, subject to such reasonable  regulations as it may
prescribe, the Trustee shall provide for the registration of Certificates and of
transfers and exchanges of Certificates as herein  provided.  Upon surrender for
registration  of  transfer  of  any  Certificate,  the  Trustee  shall  execute,
authenticate  and  deliver,  in  the  name  of  the  designated   transferee  or
transferees,  one or more new Certificates in like aggregate interest and of the
same Class.
          (b)  At  the  option  of  a  Certificateholder,  Certificates  may  be
exchanged  for  other  Certificates  of  authorized  denominations  and the same
aggregate  interest in the Trust Fund and of the same Class,  upon  surrender of
the  Certificates  to be exchanged at the office or agency of the Trustee in the
City of New York where  Certificates  may be  surrendered  for  registration  of
transfer  or  exchange.   The  Trustee  will  give  prompt   written  notice  to
Certificateholders  of any  change  in the  location  of the any such  office or
agency.  The  Trustee  initially  designates  its  offices,  located at ▇▇ ▇▇▇▇▇
▇▇▇▇▇▇,  ▇▇▇ ▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇, for such purpose.  The Certificate
Register will be kept in Chicago, Illinois at the offices of the Trustee located
at the Corporate  Trust Office and may be kept in an electronic  form capable of
printing out a hard copy of the Certificate Register.  Whenever any Certificates
are so surrendered  for exchange,  the Trustee shall execute,  authenticate  and
deliver the  Certificates  which the  Certificateholder  making the  exchange is
entitled to receive. Every Certificate presented or surrendered for registration
of transfer or exchange shall be accompanied by a written instrument of transfer
in form  satisfactory  to the Trustee duly executed by the Holder thereof or his
attorney duly authorized in writing.
          (c) No service charge to the Certificateholders  shall be made for any
registration  of  transfer or  exchange  of  Certificates,  but payment of a sum
sufficient  to cover  any tax or  governmental  charge  that may be  imposed  in
connection with any transfer or exchange of Certificates may be required.
          (d) All  Certificates  surrendered  for  registration  of transfer and
exchange  shall  be  canceled  and  subsequently  destroyed  by the  Trustee  in
accordance with the Trustee's customary procedures.
          (e) No  transfer  of any Class A, Class B-4,  Class B-5,  Class B-6 or
Class R  Certificate  shall be made unless that  transfer is made pursuant to an
effective  registration  statement under the 1933 Act and effective registration
or  qualification  under  applicable  state  securities  laws,  or is  made in a
transaction which does not require such  registration or  qualification.  In the
event that a transfer is to be made without  registration or qualification,  (i)
the Trustee shall require,  in order to assure  compliance  with such laws, that
the   Certificateholder's   prospective  transferee  and  the  Certificateholder
desiring to effect the  transfer  each  certify to the Trustee in writing in the
forms set forth in Exhibit F and Exhibit G, respectively,  the facts surrounding
the  transfer  and (ii) the  Depositor  or the Trustee may require an Opinion of
Counsel  reasonably  satisfactory to the requesting party that such transfer may
be made without such  registration  or  qualification,  which Opinion of Counsel
shall  not be  required  to be an  expense  of  the  Depositor  or the  Trustee.
Notwithstanding the foregoing, so long as the Class B-4, Class B-5 and Class B-6
Certificates are
                                      -77-
Book-Entry  Certificates,  no such  opinions or forms need to be delivered  with
respect to any proposed  transfer and any transferee  thereof shall be deemed to
have  represented to have  represented by virtue of its purchase or holding such
Certificate (or interest therein) that it is "qualified  institutional buyer" as
defined  under Rule 144A,  acting for its own  account or the  accounts of other
"qualified  institutional  buyers" as defined under Rule 144A of the  Securities
Act of 1933, as amended,  and is aware that the proposed  transferor  intends to
rely on the exemption from registration requirements under the Securities Act of
1933, as amended,  provided by Rule 144A.  Neither the Depositor nor the Trustee
is obligated to register or qualify any Class A, Class B-4, Class B-5, Class B-6
or Class I-R  Certificates  under the 1933 Act or any other securities law or to
take any action  not  otherwise  required  under  this  Agreement  to permit the
transfer of such Certificate or interest without  registration or qualification.
Any such Holder  desiring to effect such transfer  shall,  and does hereby agree
to,  indemnify  the Trustee and the  Depositor  against any  liability  that may
result if the  transfer  is not so  exempt,  or is not made in  accordance  with
federal and state laws.
          (f) No transfer of a Class A, Class R or Class I-R  Certificate  shall
be made to any  employee  benefit or other plan that is subject to the  Employee
Retirement Income Security Act of 1974, as amended ("ERISA"), or Section 4975 of
the Code,  to a trustee or other person acting on behalf of any such plan, or to
any other person using "plan assets" to effect such acquisition.  Any transferee
of a Class  B-4,  Class  B-5 or Class  B-6  Certificate  shall be deemed to have
represented  by  virtue of its  purchase  or  holding  of such  Certificate  (or
interest  therein)  that either (i) such  transferee is not a is not an employee
benefit plan or other plan subject to the prohibited  transaction  provisions of
ERISA or  Section  4975 of the Code,  or any  Person  (including  an  investment
manager,  a named  fiduciary  or a trustee of any such plan) who is using  "plan
assets" of any such plan to effect such acquisition (each, a "Plan Investor") or
(ii) such transferee is (a) an insurance  company,  (b) the source of funds used
to purchase or hold such  Certificate  (or  interest  therein) is an  "insurance
company  general  account" (as defined in U.S.  Department  of Labor  Prohibited
Transaction Class Exemption  ("PTCE") 95-60, and (c) the conditions set forth in
Sections I and III of PTCE 95-60 have been satisfied (each entity that satisfies
this clause (ii), a "Complying  Insurance  Company").  Any transferee of a Class
B-1, Class B-2 or Class B-3 Certificate  shall be deemed to have  represented by
virtue of its purchase or holding of such Certificate (or interest therein) that
either (a) such transferee is not a is not a Plan Investor,  (b) it has acquired
and is holding such Certificate in reliance on Prohibited  Transaction Exemption
("PTE") 89-90,  54 Fed. Reg. 42597 (October 17, 1989),  as amended by PTE 97-34,
62 Fed.  Reg.  39021  (July 21,  1997),  and PTE  2000-58,  65 Fed.  Reg.  67765
(November 13, 2000) (the  "Exemption"),  and that it understands  that there are
certain  conditions to the  availability  of the Exemption  including  that such
Certificate  must be rated,  at the time of purchase,  not lower that "BBB-" (or
its  equivalent)  by Standard & Poor's,  "BBB-" (or its  equivalent) by Fitch or
"Baa3" (or its  equivalent)  by ▇▇▇▇▇'▇ or (c) such  transferee  is a  Complying
Insurance Company.  If any Class B-1, Class B-2 or Class B-3 Certificate (or any
interest  therein)  is  acquired or held by any Person that does not satisfy the
conditions  described in this paragraph (f), then the last preceding  transferee
that  either  (i) is not a Plan  Investor,  (ii) with  respect to the Class B-1,
Class B-2 of Class B-3  Certificates,  acquired such  Certificate  in compliance
with the Exemption, or (iii) is a Complying Insurance Company shall be restored,
to the extent  permitted by law, to all rights and  obligations  as  Certificate
Owner  thereof  retroactive  to the  date  of  such  Transfer  of  such  Class B
Certificate.  The Trustee  shall be under no  liability to any Person for making
any payments due on such Certificate to such preceding transferee. Any purported
Certificateholder  whose  acquisition  or holding of any Class  Certificate  (or
interest therein) was effected in violation of such restrictions shall indemnify
and hold harmless the Trustee, the
                                      -78-
Servicer, Washington Mutual, any Subservicer, any underwriter and the Trust Fund
from and against any and all liabilities,  claims, costs or expenses incurred by
such parties as a result of such acquisition or holding.
          (g) Additional  restrictions on transfers of the Class R and Class I-R
Certificates to Disqualified Organizations are set forth below:
               (i) Each Person who has or who acquires any ownership interest in
a  Class  R,  Class  I-R  Certificate  shall  be  deemed  by the  acceptance  or
acquisition  of such  ownership  interest  to have  agreed  to be  bound  by the
following  provisions  and to have  irrevocably  authorized  the  Trustee or its
designee under clause (iii)(A) below to deliver  payments to a Person other than
such  Person and to  negotiate  the terms of any  mandatory  sale  under  clause
(iii)(B)  below and to execute all  instruments  of transfer and to do all other
things  necessary in  connection  with any such sale.  The rights of each Person
acquiring  any  ownership  interest  in a Class R or Class I-R  Certificate  are
expressly subject to the following provisions:
                    (A) Each Person holding or acquiring any ownership  interest
     in a Class R or Class I-R  Certificate  shall be other than a  Disqualified
     Organization  and  shall  promptly  notify  the  Trustee  of any  change or
     impending change in its status as other than a Disqualified Organization.
                    (B)  In  connection  with  any  proposed   transfer  of  any
     ownership  interest in a Class R or Class I-R Certificate to a U.S. Person,
     the  Trustee  shall  require  delivery  to it, and shall not  register  the
     transfer of a Class R or Class I-R Certificate  until its receipt of (1) an
     affidavit and agreement (a "Transferee  Affidavit and  Agreement"  attached
     hereto as Exhibit H) from the proposed  transferee,  in form and  substance
     satisfactory  to the Servicer,  representing  and  warranting,  among other
     things,  that it is not a non-U.S.  Person,  that such  transferee is other
     than a  Disqualified  Organization,  that it is not acquiring its ownership
     interest in a Class R or Class I-R  Certificate  that is the subject of the
     proposed transfer as a nominee,  trustee or agent for any Person who is not
     other than a Disqualified Organization,  that for so long as it retains its
     ownership interest in a Class R or Class I-R Certificate,  it will endeavor
     to remain other than a Disqualified Organization,  and that it has reviewed
     the provisions of this Section  6.02(g) and agrees to be bound by them, and
     (2) a certificate, attached hereto as Exhibit I, from the Holder wishing to
     transfer  a  Class R or  Class  I-R  Certificate,  in  form  and  substance
     satisfactory  to the Servicer,  representing  and  warranting,  among other
     things, that no purpose of the proposed transfer is to allow such Holder to
     impede the assessment or collection of tax.
                    (C) Notwithstanding  the delivery of a Transferee  Affidavit
     and  Agreement  by a proposed  transferee  under  clause (B) above,  if the
     Trustee has actual knowledge that the proposed transferee is not other than
     a  Disqualified  Organization,  no transfer of an  ownership  interest in a
     Class R or Class  I-R  Certificate  to such  proposed  transferee  shall be
     effected.
                    (D) Each Person holding or acquiring any ownership  interest
     in a Class R or I-R  Certificate  agrees,  by  holding  or  acquiring  such
     ownership  interest,  (1) to require a Transferee  Affidavit  and Agreement
     from the  other  Person  to whom  such  Person  attempts  to  transfer  its
     ownership  interest and to provide a certificate to the Trustee in the
                                      -79-
     form  attached  hereto as Exhibit I, and (2) to obtain the express  written
     consent of the Servicer prior to any transfer of such  ownership  interest,
     which consent may be withheld in the Servicer's sole discretion.
               (ii) The Trustee  shall  register  the transfer of any Class R or
Class I-R  Certificate  only if it shall have received the Transferee  Affidavit
and Agreement,  a certificate of the Holder requesting such transfer in the form
attached  hereto as Exhibit I and all of such other documents as shall have been
reasonably required by the Trustee as a condition to such registration.
               (iii) (A) If any Disqualified  Organization shall become a Holder
of a Class R or Class I-R  Certificate,  then the last preceding Holder that was
other  than a  Disqualified  Organization  shall  be  restored,  to  the  extent
permitted by law, to all rights and obligations as Holder thereof retroactive to
the  date  of  registration  of such  transfer  of such  Class  R or  Class  I-R
Certificate.  If any non-U.S. Person shall become a Holder of a Class R or Class
I-R  Certificate,  then the last preceding Holder that is a U.S. Person shall be
restored,  to the extent  permitted  by law,  to all rights and  obligations  as
Holder thereof  retroactive to the date of  registration of the transfer to such
non-U.S. Person of such Class R Certificate. If a transfer of a Class R or Class
I-R   Certificate  is  disregarded   pursuant  to  the  provisions  of  Treasury
Regulations Section 1.860E-1 or Section 1.860G-3, then the last preceding Holder
that was other than a Disqualified Organization shall be restored, to the extent
permitted by law, to all rights and obligations as Holder thereof retroactive to
the  date  of  registration  of such  transfer  of such  Class  R or  Class  I-R
Certificate.  The  Trustee  shall be under no  liability  to any  Person for any
registration of transfer of a Class R or Class I-R  Certificate  that is in fact
not  permitted  by this  Section  6.02(g) or for making any payments due on such
Certificate to the Holder thereof or for taking any other action with respect to
such Holder under the provisions of this Agreement.
                    (B) If any  purported  transferee  of a Class R or Class I-R
Certificate  shall become a Holder of a Class R Certificate  in violation of the
restrictions  in this  Section  6.02(g) and to the extent  that the  retroactive
restoration of the rights of the Holder of such Class R or Class I-R Certificate
as  described   in  clause   (iii)(A)   above  shall  be  invalid,   illegal  or
unenforceable,  then the Servicer  shall have the right,  without  notice to the
preceding Holder or any prior Holder of such Class R Certificate or Class I-R to
sell such  Class R or Class  I-R  Certificate  to a  purchaser  selected  by the
Servicer on such terms as the Servicer  may choose.  Such  purported  transferee
shall  promptly  endorse  and  deliver  a Class R or Class  I-R  Certificate  in
accordance  with the  instructions  of the Servicer.  Such  purchaser may be the
Servicer itself or any affiliate of the Servicer. The proceeds of such sale, net
of the commissions (which may include commissions payable to the Servicer or its
affiliates),  expenses and taxes due, if any,  shall be remitted by the Servicer
to such  purported  transferee.  The terms and conditions of any sale under this
clause (iii)(B) shall be determined in the sole discretion of the Servicer,  and
the Servicer shall not be liable to any Person having an ownership interest or a
purported  ownership  interest in a Class R or Class I-R Certificate as a result
of its exercise of such discretion.
               (iv)  The  Servicer,  on  behalf  of  the  Trustee,   shall  make
available,  upon written request from the Trustee,  all  information  reasonably
available  to it that is necessary to compute any tax imposed (A) as a result of
the transfer of an ownership  interest in a Class R or Class I-R  Certificate to
any Person  who is not other than a  Disqualified  Organization,  including  the
information  regarding "excess inclusions" of such Residual Certificate required
to be provided to the Internal  Revenue Service and certain Persons as described
in Treasury Regulation
                                      -80-
Sections 1.860E-2(a)(5) or 1.860D-1(b)(5),  and (B) as a result of any regulated
investment   company,   real  estate  investment   trust,   common  trust  fund,
partnership,  trust,  estate or  organizations  described in Section 1381 of the
Code having as among its record  holders at any time any Person who is not other
than a Disqualified  Organization.  Reasonable  compensation  for providing such
information may be required by the Servicer from such Person.
               (v) The  provisions  of this  Section  6.02(g) set forth prior to
this  Section  (v) may be  modified,  added to or  eliminated  by the  Servicer,
provided that there shall have been  delivered to the Trustee a  certificate  of
the Servicer  stating  that the Servicer has received an Opinion of Counsel,  in
form and  substance  satisfactory  to the  Servicer,  to the  effect  that  such
modification,  addition to or elimination of such  provisions will not cause the
Trust  REMIC,  REMIC I or REMIC II to cease to  qualify  as a REMIC and will not
create a risk that (i) the Trust REMIC, REMIC I or REMIC II may be subject to an
entity-level  tax caused by the  transfer of a Class R  Certificate  to a Person
which is not other than a Disqualified  Organization or (2) a  Certificateholder
or another Person will be subject to a REMIC-related  tax caused by the transfer
of applicable  Class R or Class I-R  Certificate  to a Person which is not other
than a Disqualified Organization.
               (vi) The following  legend shall appear on each Class R and Class
I-R Certificate:
          ANY RESALE,  TRANSFER OR OTHER  DISPOSITION OF THIS CERTIFICATE MAY BE
          MADE ONLY IF THE PROPOSED  TRANSFEREE PROVIDES A TRANSFER AFFIDAVIT TO
          THE SERVICER AND THE TRUSTEE THAT (1) SUCH  TRANSFEREE  IS NOT (A) THE
          UNITED STATES, ANY STATE OR POLITICAL SUBDIVISION THEREOF, ANY FOREIGN
          GOVERNMENT,   ANY  INTERNATIONAL   ORGANIZATION,   OR  ANY  AGENCY  OR
          INSTRUMENTALITY OF ANY OF THE FOREGOING,  (B) ANY ORGANIZATION  (OTHER
          THAN A  COOPERATIVE  DESCRIBED  IN SECTION  521 OF THE CODE)  WHICH IS
          EXEMPT  FROM THE TAXES  IMPOSED BY CHAPTER 1 OF THE CODE  UNLESS  SUCH
          ORGANIZATION IS SUBJECT TO THE TAX IMPOSED BY SECTION 511 OF THE CODE,
          (C) ANY  ORGANIZATION  DESCRIBED IN SECTION  1381(a)(2)(C) OF THE CODE
          (ANY SUCH PERSON  DESCRIBED IN THE FOREGOING  CLAUSES (A), (B), OR (C)
          BEING HEREINAFTER  REFERRED TO AS A "DISQUALIFIED  ORGANIZATION"),  OR
          (D) AN AGENT OF A DISQUALIFIED ORGANIZATION AND (2) NO PURPOSE OF SUCH
          TRANSFER  IS TO ENABLE  THE  TRANSFEROR  TO IMPEDE THE  ASSESSMENT  OR
          COLLECTION   OF   TAX.   SUCH   AFFIDAVIT    SHALL   INCLUDE   CERTAIN
          REPRESENTATIONS  AS  TO  THE  FINANCIAL   CONDITION  OF  THE  PROPOSED
          TRANSFEREE.   NOTWITHSTANDING  THE  REGISTRATION  IN  THE  CERTIFICATE
          REGISTER OF ANY TRANSFER,  SALE OR OTHER  DISPOSITION  OF THIS CLASS R
          CERTIFICATE  TO  A  DISQUALIFIED   ORGANIZATION   OR  AN  AGENT  OF  A
          DISQUALIFIED ORGANIZATION,  SUCH REGISTRATION SHALL BE DEEMED TO BE OF
          NO LEGAL  FORCE OR  EFFECT  WHATSOEVER  AND SUCH  PERSON  SHALL NOT BE
          DEEMED TO BE A CERTIFICATEHOLDER FOR ANY PURPOSE HEREUNDER, INCLUDING,
          BUT NOT LIMITED TO, THE RECEIPT OF DISTRIBUTIONS ON THIS
                                      -81-
          CERTIFICATE.  EACH HOLDER OF THE CLASS R CERTIFICATE  BY ACCEPTANCE OF
          THIS  CERTIFICATE  SHALL BE DEEMED TO HAVE CONSENTED TO THE PROVISIONS
          OF THIS PARAGRAPH.
          (h) The Trustee shall have no liability to the Trust Fund arising from
a transfer of any such Certificate in reliance upon a  certification,  ruling or
Opinion of Counsel described in this Section 6.02; provided,  however,  that the
Trustee  shall not register the  transfer of any Class R  Certificate  if it has
actual knowledge that the proposed  transferee does not meet the  qualifications
of a  permitted  Holder of a Class R  Certificate  as set forth in this  Section
6.02.
          (i) Except as provided below, the Book-Entry Certificates shall at all
times remain  registered in the name of the Depository or its nominee and at all
times:  (u)  registration  of the  Certificates  may not be  transferred  by the
Trustee  except  to  another  Depository;  (v)  the  Depository  shall  maintain
book-entry  records with respect to the  Certificate  Owners and with respect to
ownership  and  transfers of such  Book-Entry  Certificates;  (w)  ownership and
transfers of  registration  of the Book-Entry  Certificates  on the books of the
Depository shall be governed by applicable rules  established by the Depository;
(x) the  Depository  may  collect  its usual and  customary  fees,  charges  and
expenses from its Depository  Participants;  (y) the Trustee shall deal with the
Depository,   Depository   Participants  and  indirect  participating  firms  as
representatives  of the Certificate  Owners of the Book-Entry  Certificates  for
purposes of exercising the rights of holders under this Agreement,  and requests
and directions for and votes of such  representatives  shall not be deemed to be
inconsistent if they are made with respect to different  Certificate Owners; and
(z) the  Trustee  may  rely  and  shall  be  fully  protected  in  relying  upon
information   furnished  by  the  Depository  with  respect  to  its  Depository
Participants  and  furnished  by the  Depository  Participants  with  respect to
indirect  participating  firms and persons  shown on the books of such  indirect
participating firms as direct or indirect Certificate Owners.
     All transfers by  Certificate  Owners of Book-Entry  Certificates  shall be
made in accordance with the procedures established by the Depository Participant
or  brokerage  firm  representing   such  Certificate   Owner.  Each  Depository
Participant shall only transfer Book-Entry Certificates of Certificate Owners it
represents or of brokerage  firms for which it acts as agent in accordance  with
the Depository's normal procedures.
     If (x) (i) the  Depository or the Depositor  advises the Trustee in writing
that the  Depository  is no longer  willing or able to  properly  discharge  its
responsibilities as Depository,  and (ii) the Trustee or the Depositor is unable
to locate a qualified  successor,  (y) the  Depositor at its option  advises the
Trustee in writing that it elects to terminate the book-entry system through the
Depository  or (z)  after the  occurrence  of an Event of  Default,  Certificate
Owners  representing at least 51% of the  Certificate  Balance of the Book-Entry
Certificates  together  advise  the  Trustee  and  the  Depository  through  the
Depository  Participants in writing that the continuation of a book-entry system
through the  Depository  is no longer in the best  interests of the  Certificate
Owners, the Trustee shall notify all Certificate Owners, through the Depository,
of the  occurrence  of any such  event and of the  availability  of  definitive,
fully-registered  Certificates  (the "Definitive  Certificates")  to Certificate
Owners  requesting the same.  Upon surrender to the Trustee of the related Class
of  Certificates  by the Depository,  accompanied by the  instructions  from the
Depository   for   registration,   the  Trustee   shall  issue  the   Definitive
Certificates. None of the Originator, the Servicer, the Depositor or the Trustee
shall be  liable  for any delay in  delivery  of such  instruction  and each may
conclusively  rely on, and shall be protected in relying on, such  instructions.
The  Depositor  shall
                                      -82-
provide the Trustee with an adequate inventory of certificates to facilitate the
issuance  and  transfer  of  Definitive  Certificates.   Upon  the  issuance  of
Definitive  Certificates all references herein to obligations imposed upon or to
be performed by the Depository  shall be deemed to be imposed upon and performed
by the  Trustee,  to the  extent  applicable  with  respect  to such  Definitive
Certificates  and the Trustee  shall  recognize  the  Holders of the  Definitive
Certificates as  Certificateholders  hereunder;  provided that the Trustee shall
not by virtue of its assumption of such  obligations  become liable to any party
for any act or failure to act of the Depository.
     SECTION 6.03 MUTILATED, DESTROYED, LOST OR STOLEN CERTIFICATES.
          If (a) any mutilated Certificate is surrendered to the Trustee, or the
Trustee receives evidence to its satisfaction of the destruction,  loss or theft
of any  Certificate  and (b) there is  delivered to the Servicer and the Trustee
such  security  or  indemnity  as may be  required  by them to save each of them
harmless,  then,  in the absence of notice to the Trustee that such  Certificate
has  been  acquired  by a  bona  fide  purchaser,  the  Trustee  shall  execute,
authenticate  and  deliver,  in exchange  for or in lieu of any such  mutilated,
destroyed,  lost or stolen  Certificate,  a new  Certificate  of like  tenor and
interest  in the  Trust  Fund.  In  connection  with  the  issuance  of any  new
Certificate  under this Section  6.03,  the Trustee may require the payment of a
sum sufficient to cover any tax or other governmental charge that may be imposed
in relation  thereto and any other expenses  (including the fees and expenses of
the Trustee) connected therewith. Any replacement Certificate issued pursuant to
this  Section  6.03 shall  constitute  complete  and  indefeasible  evidence  of
ownership in the Trust Fund, as if originally  issued,  whether or not the lost,
stolen or destroyed Certificate shall be found at any time.
     SECTION 6.04 PERSONS DEEMED OWNERS.
          Prior  to  due  presentation  of a  Certificate  for  registration  of
transfer,  the  Servicer,  the  Trustee,  and any agent of the  Servicer  or the
Trustee may treat the person in whose name any  Certificate is registered as the
owner of such Certificate for the purpose of receiving distributions as provided
in this  Agreement  and for all  other  purposes  whatsoever,  and  neither  the
Servicer,  the  Trustee nor any agent of the  Servicer  or the Trustee  shall be
affected by any notice to the contrary.
     SECTION 6.05 ACCESS TO LIST OF CERTIFICATEHOLDERS' NAMES AND ADDRESSES.
          (a) If three or more  Certificateholders  (i) request in writing  from
the Trustee a list of the names and addresses of Certificateholders,  (ii) state
that such Certificateholders desire to communicate with other Certificateholders
with respect to their rights under this Agreement or under the  Certificates and
(iii) provide a copy of the communication which such Certificateholders  propose
to transmit,  then the Trustee shall, within ten Business Days after the receipt
of such request,  afford such  Certificateholders  access during normal business
hours to a current list of the Certificateholders.  The expense of providing any
such  information  requested  by a  Certificateholder  shall  be  borne  by  the
Certificateholders  requesting  such  information  and shall not be borne by the
Trustee. Every Certificateholder, by receiving and holding a Certificate, agrees
that the Trustee shall not be held  accountable  by reason of the  disclosure of
any  such  information  as to  the  list  of the  Certificateholders  hereunder,
regardless of the source from which such information was derived.
                                      -83-
          (b) The Servicer, so long as it is the Servicer hereunder,  shall have
unlimited access to a list of the names and addresses of the  Certificateholders
which list shall be  provided by the  Trustee  promptly  upon the request of the
Servicer.
     SECTION 6.06 MAINTENANCE OF OFFICE OR AGENCY.
          The Trustee will  maintain or cause to be maintained at its expense an
office or offices or agency or agencies  where  Certificates  may be surrendered
for  registration  of transfer or exchange  and where  notices and demands to or
upon the  Trustee in  respect  of the  Certificates  and this  Agreement  may be
served. The Trustee initially designates the office described in Section 9.11 as
its office for such purpose.  The Trustee will give prompt written notice to the
Certificateholders of any change in the location of any such office or agency.
                                  ARTICLE VII
                     THE DEPOSITOR, SELLER AND THE SERVICER
     SECTION 7.01 LIABILITIES OF THE DEPOSITOR, SELLER AND THE SERVICER.
          The  Depositor,  Seller  and the  Servicer  shall  each be  liable  in
accordance  herewith  only to the  extent of the  obligations  specifically  and
respectively imposed upon and undertaken by them herein.
          It is understood and agreed that the  obligation  under this Agreement
of the Seller or the Servicer to repurchase  or substitute  any Mortgage Loan as
to which any breach of  representation  or warranty made in Section 2.01,  2.02,
2.03 or 2.04 of this  Agreement  or in Section 2 of the Mortgage  Loan  Purchase
Agreement has occurred and is continuing shall constitute the sole and exclusive
remedy respecting such breach available to the Depositor, the Certificateholders
or the Trustee on their behalf so long as the Seller  repurchases or substitutes
any such Mortgage Loan and such Certificateholders  shall not be entitled to any
consequential damages.
          Without limiting the effect of the preceding  paragraph,  the Servicer
shall defend and  indemnify  the Trust Fund,  the Trustee,  the  Depositor,  the
Certificate Registrar, the Seller and the Certificateholders against any and all
costs, expenses,  losses, damages,  claims or liabilities,  including reasonable
fees and  expenses of counsel and  expenses of  litigation,  arising  from third
party claims or actions (including penalties or fees imposed by any governmental
or  regulatory  body or  agency)  in  respect  of any  breach of the  Servicer's
covenants,  representations  or warranties set forth herein or in respect of any
action  taken or omitted by the  Servicer  with  respect  to any  Mortgage  Loan
constituting  a failure by the  Servicer to perform its  obligations  under this
Agreement.  This indemnity  shall survive any Event of Default (but a Servicer's
obligations  under this  Section  7.01  shall not  relate to any  actions of any
predecessor or subsequent Servicer after an Event of Default) and any payment of
the amount owing under,  or any repurchase by the Servicer of, any such Mortgage
Loan.
          Without  limiting the effect of the second  preceding  paragraph,  the
Seller shall defend and indemnify the Trust Fund,  the Trustee,  the  Depositor,
the Certificate Registrar,  the Servicer and the Certificateholders  against any
and all costs,  expenses,  losses,  damages,  claims or  liabilities,  including
reasonable fees and expenses of counsel and expenses of litigation, arising from
third  party
                                      -84-
claims or actions  (including  penalties or fees imposed by any  governmental or
regulatory  body or agency) in respect of any breach of the Seller's  covenants,
representations or warranties set forth herein or in respect of any action taken
or omitted by the  Seller  with  respect to any  Mortgage  Loan  constituting  a
failure by the Seller to perform  its  obligations  under this  Agreement.  This
indemnity shall survive any payment of the amount owing under, or any repurchase
by the Seller of, any such Mortgage Loan.
          Any amounts  received  by the  Trustee  from the Seller or Servicer on
behalf of the Trust Fund  pursuant to this Article VII shall be deposited in the
Certificate   Account  and  shall  be  distributed  as  part  of  the  Available
Distribution Amount. If either the Seller or the Servicer has made any indemnity
payments to the Trustee pursuant to this Article VII and the Trustee  thereafter
collects any of such  amounts  from others,  the Trustee will repay such amounts
collected to the Seller or Servicer,  as applicable,  together with any interest
collected thereon.
     SECTION 7.02 MERGER OR  CONSOLIDATION  OF THE DEPOSITOR,  THE SELLER OR THE
SERVICER.
          Subject to the next succeeding  paragraph,  the Depositor,  the Seller
and the  Servicer  will  each do or  cause to be done all  things  necessary  to
preserve and keep in full force and effect its existence,  rights and franchises
(charter and statutory) and will each obtain and preserve its  qualification  to
do  business  as a  foreign  corporation  in each  jurisdiction  in  which  such
qualification   is  or  shall  be   necessary   to  protect  the   validity  and
enforceability  of this  Agreement,  or any of the Mortgage Loans and to perform
its respective duties under this Agreement.
          Any of  the  Seller,  the  Servicer  or the  Depositor  may  merge  or
consolidate with any Person,  and any Person into which the Seller, the Servicer
or the Depositor may be merged or consolidated, or any Person resulting from any
merger or consolidation to which the Seller or the Servicer shall be a party, or
any Person succeeding to the business of the Seller,  Servicer or the Depositor,
shall be the successor of the Seller, the Servicer or the Depositor, as the case
may be,  hereunder,  without the execution or filing of any paper or any further
act on the part of any of the parties  hereto,  anything  herein to the contrary
notwithstanding;  PROVIDED,  HOWEVER,  that the successor or surviving Person to
the  Servicer  shall be  qualified  to sell  mortgage  loans to,  and to service
mortgage loans on behalf of, ▇▇▇▇▇▇ ▇▇▇ or Freddie Mac.
          Notwithstanding  anything else in this Section 7.02 or in Section 7.04
hereof to the  contrary,  the  Servicer  may assign its rights and  delegate its
duties and  obligations  under this Agreement  (except for the obligation of the
Servicer or Seller to effectuate  repurchases or substitutions of Mortgage Loans
hereunder,  including pursuant to Section 2.01, 2.02 or 2.04 hereof, which shall
remain with Washington Mutual hereunder);  PROVIDED,  HOWEVER, that the Servicer
gives the  Depositor  and the Trustee  notice of such  assignment;  and PROVIDED
FURTHER,  that such  purchaser  or  transferee  accepting  such  assignment  and
delegation shall be an institution that is a ▇▇▇▇▇▇ ▇▇▇ and Freddie Mac approved
seller/servicer in good standing, which has a net worth of at least $15,000,000,
and which is willing to service the Mortgage  Loans and executes and delivers to
the  Depositor  and the  Trustee an  agreement  accepting  such  delegation  and
assignment,  which contains an assumption by such Person of the rights,  powers,
duties, responsibilities, obligations and liabilities of the Servicer, with like
effect as if originally  named as a party to this Agreement.  In the case of any
such  assignment  and  delegation,  the  Servicer  shall  be  released  from its
obligations  under this Agreement  (except as provided  above),  except that the
Servicer shall remain liable for all liabilities
                                      -85-
and obligations  incurred by it as Servicer  hereunder prior to the satisfaction
of the  conditions to such  assignment and delegation set forth in the preceding
sentence.
     SECTION 7.03  LIMITATION  ON LIABILITY OF THE  DEPOSITOR,  THE SERVICER AND
OTHERS.
          Neither  the  Depositor  nor the  Servicer  nor any of the  directors,
officers,  employees or agents of the  Depositor or the Servicer  shall be under
any liability to the  Certificateholders  for any action taken or for refraining
from the taking of any action in good faith pursuant to this  Agreement,  or for
errors in judgment; PROVIDED, HOWEVER, that this provision shall not protect the
Depositor or the Servicer  against any breach of  representations  or warranties
made by it herein or protect the  Depositor  or the  Servicer or any such person
from any  liability  which  would  otherwise  be  imposed  by reasons of willful
misfeasance,  bad faith or negligence in the  performance of duties or by reason
of reckless  disregard of obligations and duties hereunder.  The Depositor,  the
Servicer and any  director,  officer,  employee or agent of the Depositor or the
Servicer may rely in good faith on any document of any kind prima facie properly
executed and submitted by any Person  respecting any matters arising  hereunder.
The Depositor, the Servicer and any director,  officer, employee or agent of the
Depositor  or the  Servicer  shall be  indemnified  by the  Trust  Fund and held
harmless against any loss,  liability or expense incurred in connection with any
legal  action  relating to this  Agreement or the  Certificates,  other than any
loss, liability or expense incurred by reason of willful misfeasance,  bad faith
or negligence in the  performance  of duties  hereunder or by reason of reckless
disregard of  obligations  and duties  hereunder.  Neither the Depositor nor the
Servicer  shall be under any  obligation  to appear in,  prosecute or defend any
legal action that is not  incidental to their  respective  duties  hereunder and
which in its  opinion  may  involve it in any  expense or  liability;  provided,
however,  that  either  the  Depositor  or the  Servicer  may in its  discretion
undertake any such action that it may deem  necessary or desirable in respect of
this  Agreement and the rights and duties of the parties hereto and interests of
the Trustee and the Certificateholders hereunder.
     SECTION 7.04 SERVICER NOT TO RESIGN.
          The Servicer shall not resign from the  obligations and duties imposed
upon it hereunder  except upon  determination  that such  obligations and duties
hereunder are no longer permissible under applicable law or except in connection
with a permitted  assignment  pursuant to Section 7.02.  Any such  determination
that the Servicer's  obligations are no longer permissible shall be evidenced by
an Opinion of Counsel to such effect  delivered  to the  Trustee.  The  Servicer
shall  give  notice  of  any   proposed   resignation   to  the   Trustee,   the
Certificateholders  and,  so long as any  Class  I-A or Class B  Certificate  is
outstanding,  the Rating  Agencies.  No such  resignation  by the Servicer shall
become  effective  until the Trustee or a successor  servicer shall have assumed
the Servicer's  responsibilities and obligations in accordance with Section 8.02
hereof or shall affect any obligation of the Seller hereunder.
     SECTION 7.05 ERRORS AND OMISSIONS INSURANCE; FIDELITY BONDS.
          The  Servicer  shall,  for so long as it acts as  servicer  under this
Agreement,  obtain and  maintain in force (a) a policy or policies of  insurance
covering  errors and omissions in the performance of its obligations as servicer
hereunder,  and (b) a fidelity  bond in respect of its  officers,  employees and
agents. Each such policy or policies and bond shall,  together,  comply with the
requirements  from  time  to time  of  ▇▇▇▇▇▇  ▇▇▇ or  Freddie  Mac for  persons
performing  servicing for mortgage loans purchased by ▇▇▇▇▇▇ ▇▇▇ or Freddie Mac.
In the event that any such policy or bond
                                      -86-
ceases to be in effect,  the  Servicer  shall  obtain a  comparable  replacement
policy or bond from an insurer or issuer,  meeting  the  requirements  set forth
above as of the date of such replacement.
     SECTION 7.06 SELLER AND SERVICER MAY OWN CERTIFICATES.
          Each of the Seller and the  Servicer  in its  individual  or any other
capacity may become the owner or pledgee of Certificates with the same rights as
it would have if it were not the Seller or the Servicer, as the case may be.
                                  ARTICLE VIII
                                     DEFAULT
     SECTION 8.01 EVENTS OF DEFAULT.
          "Event  of  Default,"  wherever  used  herein,  means  any  one of the
following events (whatever reason for such Event of Default and whether it shall
be  voluntary or  involuntary  or be effected by operation of law or pursuant to
any judgment,  decree or order of any court or any order,  rule or regulation of
any administrative or governmental body):
          (a) any  failure by the  Servicer  to remit to the Trustee any payment
other than a Monthly Advance required to be made by the Servicer under the terms
of this Agreement, which failure shall continue unremedied for a period of three
Business  Days after the date upon which  written  notice of such failure  shall
have been  given to the  Servicer  by the  Trustee  or the  Depositor  or to the
Servicer and the Trustee by the Holders of Certificates having not less than 25%
of the Voting Rights evidenced by the Certificates; or
          (b) any failure by the  Servicer to observe or perform in any material
respect any other of the  covenants  or  agreements  on the part of the Servicer
contained in this Agreement (except as set forth in (c) below) which failure (i)
materially affects the rights of the  Certificateholders and (ii) shall continue
unremedied  for a period of 60 days  after the date on which  written  notice of
such  failure  shall  have been  given to the  Servicer  by the  Trustee  or the
Depositor,  or to the  Servicer  and the Trustee by the Holders of  Certificates
evidencing not less than 25% of the Voting Rights evidenced by the Certificates;
or
          (c) if a  representation  or warranty set forth in Section 2.03 hereof
shall prove to be  materially  incorrect as of the time made in any respect that
materially and adversely  affects interests of the  Certificateholders,  and the
circumstances or condition in respect of which such  representation  or warranty
was incorrect shall not have been eliminated or cured, or the affected  Mortgage
Loan shall not have been substituted for or repurchased,  within 60 days (or, is
such breach is not  capable of being cured  within 60 days and is not subject to
the remedies set forth in Section 2.04 and provided  that the Servicer  believes
in good faith that such breach can be cured and is diligently  pursuing the cure
thereof,  within 120 days) after the date on which written  notice thereof shall
have been given to the Servicer and Seller by the Trustee for the benefit of the
Certificateholders or by the Depositor; or
          (d) a decree or order of a court or agency  or  supervisory  authority
having  jurisdiction  in the premises for the  appointment  of a conservator  or
receiver or liquidator in any insolvency,  readjustment of debt,  marshalling of
assets  and  liabilities  or  similar  proceedings,  or for
                                      -87-
the winding-up or liquidation  of its affairs,  shall have been entered  against
the Servicer and such decree or order shall have remained in force  undischarged
or unstayed for a period of 60 days; or
          (e) the Servicer shall consent to the  appointment of a conservator or
receiver or liquidator in any insolvency,  readjustment of debt,  marshalling of
assets and liabilities or similar  proceedings of or relating to the Servicer or
all or substantially all of the property of the Servicer; or
          (f) the Servicer shall admit in writing its inability to pay its debts
generally as they become due, file a petition to take  advantage of, or commence
a voluntary case under,  any applicable  insolvency or  reorganization  statute,
make an assignment  for the benefit of its  creditors,  or  voluntarily  suspend
payment of its obligations; or
          (g) any failure of the  Servicer  to make any  Monthly  Advance in the
manner and at the time  required to be made from its own funds  pursuant to this
Agreement and after receipt of notice from the Trustee pursuant to Section 5.04,
which failure  continues  unremedied after the close of business on the Business
Day immediately preceding the Distribution Date.
          If an Event of Default due to the actions or inaction of the  Servicer
described in clauses (a) through (f) of this Section shall occur,  then,  and in
each and every such case,  so long as such Event of Default  shall not have been
remedied,  the Trustee  shall,  if so  directed  by the Holders of  Certificates
evidencing not less than 25% of the Voting Rights evidenced by the Certificates,
by notice in writing to the Servicer (and so long as the Class I-A and the Class
B Certificates  are outstanding with a copy to the Rating  Agencies),  terminate
all of the rights and  obligations of the Servicer  under this Agreement  (other
than rights to reimbursement  for Monthly Advances or other advances  previously
made, as provided in Section 3.09 or 4.01).
          If an Event of  Default  described  in  clause  (g) shall  occur,  the
Trustee shall,  prior to the next  Distribution  Date,  terminate the rights and
obligations of the Servicer  hereunder (other than rights to  reimbursement  for
Monthly Advances or other advances  previously made, as provided in Section 3.09
or 4.01) and succeed to the rights and  obligations  of the  Servicer  hereunder
pursuant to Section 8.02,  including the obligation to make Monthly  Advances on
such Distribution Date pursuant to the terms hereof.
     SECTION 8.02 TRUSTEE TO ACT; APPOINTMENT OF SUCCESSOR.
          On and after the time the  Servicer  receives a notice of  termination
pursuant to Section  8.01 hereof or resigns  pursuant  to Section  7.04  hereof,
subject to the  provisions  of Section  3.06  hereof,  the Trustee  shall be the
successor in all respects to the Servicer in its capacity as servicer under this
Agreement and with respect to the  transactions set forth or provided for herein
and  shall  be  subject  to all the  responsibilities,  duties  and  liabilities
relating  thereto  placed on the  Servicer by the terms and  provisions  hereof,
provided  that  neither  the  Trustee nor any other  successor  to the  Servicer
pursuant to this Section 8.02 shall be deemed to have made any representation or
warranty  made by the Servicer,  shall be obligated to effect any  repurchase or
substitute of any Mortgage Loan, or shall have any  responsibility for an act or
omission of any  predecessor  Servicer.  As compensation  therefor,  the Trustee
shall be entitled to all funds  relating to the Mortgage Loans that the Servicer
would  have been  entitled  to charge to the  related  Custodial  Account if the
Servicer had continued to act  hereunder  (except that the  terminated  Servicer
shall  retain  the  right to be  reimbursed  for  advances  (including,  without
limitation,  Monthly Advances)
                                      -88-
theretofore  made by the Servicer  with respect to which it would be entitled to
be reimbursed if it had not been so terminated as Servicer). Notwithstanding the
foregoing, if the Trustee has become the successor to the Servicer in accordance
with this Section 8.02,  the Trustee may, if it shall be unwilling to so act, or
shall, if it is unable to so act (exclusive of the  obligations  with respect to
Monthly  Advances),  appoint,  or petition a court of competent  jurisdiction to
appoint, any established mortgage loan servicing institution, the appointment of
which does not adversely affect the then current rating of the Certificates,  as
the successor to the Servicer  hereunder in the assumption of all or any part of
the responsibilities, duties or liabilities of the Servicer. Pending appointment
of a successor to the  Servicer  hereunder,  the Trustee,  unless the Trustee is
prohibited by law from so acting, shall act in such capacity as provided herein.
In connection with such  appointment  and assumption,  the Trustee may make such
arrangements  for the compensation of such successor out of payments on Mortgage
Loans as it and such  successor  shall agree;  PROVIDED,  HOWEVER,  that no such
compensation  shall be in excess of that permitted the Servicer  hereunder.  The
Trustee  and such  successor  shall  take  such  action,  consistent  with  this
Agreement, as shall be necessary to effectuate any such succession.
          The Servicer  that has been  terminated  shall,  at the request of the
Trustee but at the expense of such  Servicer,  deliver to the assuming party all
documents and records relating to each  Sub-Servicing  Agreement and the related
Mortgage  Loans  and an  accounting  of  amounts  collected  and  held by it and
otherwise use its best efforts to effect the orderly and  efficient  transfer of
each Sub-Servicing Agreement to the assuming party.
          The  Servicer  shall  cooperate  with the  Trustee  and any  successor
servicer in effecting the  termination  of the Servicer's  responsibilities  and
rights hereunder,  including without limitation,  the transfer to such successor
for administration by it of all cash amounts which shall at the time be credited
by the Servicer to the Custodial Account or thereafter  received with respect to
the Mortgage Loans and the Servicer Mortgage Files.
          Neither the Trustee nor any other  successor  servicer shall be deemed
to be in default  hereunder  by reason of any  failure to make,  or any delay in
making,  any  distribution  hereunder or any portion  thereof  caused by (a) the
failure  of the  Servicer  to (i)  deliver,  or any delay in  delivering,  cash,
documents  or records to it, (ii)  cooperate as required by this  Agreement,  or
(iii)  deliver the  Servicer  Mortgage  Files to the Trustee as required by this
Agreement,  or (b)  restrictions  imposed  by any  regulatory  authority  having
jurisdiction over the Servicer.
          Any successor to the Servicer as servicer shall during the term of its
service as servicer  maintain in force the policy or policies  that the Servicer
is required to maintain  pursuant to Section 7.05 hereof.  No termination of the
Servicer shall have any affect on the obligations of the Seller hereunder.
     SECTION 8.03 NOTIFICATION TO CERTIFICATEHOLDERS.
          (a)  Upon  any  termination  or  appointment  of a  successor  to  the
Servicer,   the  Trustee  shall  give  prompt  written  notice  thereof  to  the
Certificateholders  at their respective  addresses  appearing in the Certificate
Register  and,  so  long as the  Class  I-A and  the  Class B  Certificates  are
outstanding, to the Rating Agencies.
                                      -89-
          (b) Within 2 Business  Days after its notice of the  occurrence of any
Event of Default,  the Trustee shall transmit by mail to all  Certificateholders
and, so long as the Class I-A and the Class B Certificates are  outstanding,  to
the Rating Agencies notice of each such Event of Default  hereunder known to the
Trustee, unless such Event of Default shall have been cured or waived.
     SECTION 8.04 WAIVER OF EVENTS OF DEFAULT.
          The  Holders  representing  at least  66-2/3% of the Voting  Rights of
Certificates  affected by a default or Event of Default  hereunder may waive any
default or Event of Default,  PROVIDED,  HOWEVER, that (a) a default or Event of
Default under clause (a) or (g) of Section 8.01 may be waived only by Holders of
Certificates of 66-2/3 of the Class affected by such default or Event of Default
and (b) no waiver  pursuant  to this  Section  8.04 shall  affect the Holders of
Certificates in the manner set forth in Section 11.01(b)(i), (ii) or (iii). Upon
any such waiver of a default or Event of Default by the Holders representing the
requisite  percentage of Voting Rights of Certificates  affected by such default
or Event of Default,  such default or Event of Default  shall cease to exist and
shall be deemed to have been  remedied  for  every  purpose  hereunder.  No such
waiver shall extend to any  subsequent  or other  default or Event of Default or
impair any right consequent thereon except to the extent expressly so waived.
                                   ARTICLE IX
                             CONCERNING THE TRUSTEE
     SECTION 9.01 DUTIES OF TRUSTEE.
          The Trustee,  prior to the occurrence of an Event of Default and after
the curing or waiver of all Events of Default that may have occurred, undertakes
with  respect to the Trust Fund to perform  such  duties and only such duties as
are  specifically  set forth in this Agreement.  In case an Event of Default has
occurred and remains uncured and not waived,  the Trustee shall exercise such of
the rights and powers vested in it by this Agreement, and use the same degree of
care and skill in their  exercise,  as a prudent  person  would  exercise or use
under the  circumstances  in the  conduct  of such  person's  own  affairs.  Any
permissive  right of the  Trustee  set  forth  in this  Agreement  shall  not be
construed as a duty.
          The   Trustee,   upon  receipt  of  all   resolutions,   certificates,
statements,  opinions, reports, documents, orders or other instruments furnished
to the Trustee that are  specifically  required to be furnished  pursuant to any
provision of this Agreement shall examine them to determine whether they conform
to the  requirements  of  this  Agreement.  The  Trustee  shall  have no duty to
recompute,  recalculate or verify the accuracy of any  resolution,  certificate,
statement,  opinion, report, document, order or other instrument so furnished to
the Trustee.
          No  provision  of this  Agreement  shall be  construed  to relieve the
Trustee from liability for its own negligent  action,  its own negligent failure
to act or its own misconduct,  its negligent  failure to perform its obligations
in compliance  with this  Agreement,  or any liability which would be imposed by
reason of its willful misfeasance or bad faith; PROVIDED, HOWEVER, that:
          (a)  prior to the  occurrence  of an Event of  Default,  and after the
curing or  waiver of all such  Events of  Default  that may have  occurred,  the
duties and obligations of the Trustee shall
                                      -90-
be determined  solely by the express  provisions of this Agreement,  the Trustee
shall not be  personally  liable except for the  performance  of such duties and
obligations  as are  specifically  set  forth  in  this  Agreement,  no  implied
covenants or obligations  shall be read into this Agreement  against the Trustee
and the Trustee may conclusively rely, as to the truth of the statements and the
correctness of the opinions expressed therein, upon any certificates or opinions
furnished to the Trustee and  conforming to the  requirements  of this Agreement
which it  reasonably  believed in good faith to be genuine and to have been duly
executed by the proper authorities respecting any matters arising hereunder;
          (b) the  Trustee  shall  not be  personally  liable  for an  error  of
judgment made in good faith by a Responsible Officer or Responsible  Officers of
the  Trustee,  unless the  Trustee was  negligent  or acted in bad faith or with
willful misfeasance;
          (c) the Trustee  shall not be  personally  liable with  respect to any
action taken,  suffered or omitted to be taken by it in good faith in accordance
with the direction of Holders of  Certificates  evidencing  not less than 25% of
the Voting Rights allocated to each Class of Certificates  relating to the time,
method and place of conducting any  proceeding  for any remedy  available to the
Trustee, or exercising any trust or power conferred upon the Trustee, under this
Agreement; and
          (d) no provision of this Agreement shall require the Trustee to expend
or risk  its own  funds  or  otherwise  incur  any  financial  liability  in the
performance  of any of its duties  hereunder  or in the  exercise  of any of its
rights  or  powers  if it shall  have  reasonable  grounds  for  believing  that
repayment of such funds or adequate  indemnity against such risk or liability is
not reasonably assured to it.
          Except with respect to an Event of Default  described in clause (a) of
Section 8.01,  the Trustee shall not be deemed to have knowledge of any Event of
Default or event which,  with notice or lapse of time, or both,  would become an
Event of  Default,  unless a  Responsible  Officer  of the  Trustee  shall  have
received  written  notice  thereof  from  the  Servicer,   the  Depositor  or  a
Certificateholder,  or a  Responsible  Officer of the Trustee has actual  notice
thereof,  and in the absence of such notice no provision  hereof  requiring  the
taking of any action or the  assumption of any duties or  responsibility  by the
Trustee  following the  occurrence of any Event of Default or event which,  with
notice  or lapse of time or both,  would  become an Event of  Default,  shall be
effective as to the Trustee.
          The  Trustee  shall  have  no  duty  hereunder  with  respect  to  any
complaint,  claim, demand,  notice or other document it may receive or which may
be  alleged  to have been  delivered  to or served  upon it by the  parties as a
consequence of the assignment of any Mortgage Loan hereunder; provided, however,
that the  Trustee  shall use its best  efforts  to remit to the  Servicer,  upon
receipt, any such complaint,  claim, demand,  notice or other document (i) which
is delivered  to the  Corporate  Trust  Office of the  Trustee,  (ii) of which a
Responsible Officer has actual knowledge,  and (iii) which contains  information
sufficient to permit the Trustee to make a determination  that the real property
to which such document relates is a Mortgaged Property.
                                      -91-
     SECTION 9.02 CERTAIN MATTERS AFFECTING THE TRUSTEE.
          (a) Except as otherwise provided in Section 9.01:
               (i) the Trustee may request and rely upon and shall be  protected
in acting or refraining from acting upon any resolution,  Officers' Certificate,
certificate of Servicing Officers, auditors or any other certificate, statement,
instrument, opinion, report, notice, request, consent, order, appraisal, bond or
other paper or document  believed by it to be genuine and to have been signed or
presented by the proper party or parties;
               (ii) the  Trustee  may  consult  with  counsel or any  Opinion of
Counsel shall be full and complete  authorization  and  protection in respect of
any action  taken or  suffered or omitted by it  hereunder  in good faith and in
accordance with such Opinion of Counsel;
               (iii) the Trustee shall be under no obligation to exercise any of
the trusts or powers vested in it by this Agreement or to institute,  conduct or
defend any litigation  hereunder or in relation hereto at the request,  order or
direction of any of the  Certificateholders,  pursuant to the provisions of this
Agreement,  unless  such  Certificateholders  shall have  offered to the Trustee
reasonable  security or indemnity  against the costs,  expenses and  liabilities
which may be  incurred  therein or  thereby;  nothing  contained  herein  shall,
however, relieve the Trustee of the obligation,  upon the occurrence of an Event
of Default (which has not been cured or waived),  to exercise such of the rights
and powers  vested in it by this  Agreement,  and to use the same degree of care
and skill in their  exercise as a prudent person would exercise or use under the
circumstances in the conduct of such person's own affairs;
               (iv) the Trustee  shall not be  personally  liable for any action
taken,  suffered  or  omitted  by it in  good  faith  and  believed  by it to be
authorized  or within the  discretion or rights or powers  conferred  upon it by
this Agreement;
               (v) prior to the occurrence of an Event of Default  hereunder and
after the curing or waiving of all Events of Default that may have occurred, the
Trustee shall not be bound to make any  investigation  into the facts or matters
stated in any resolution,  certificate,  statement, instrument, opinion, report,
notice,  request,  consent,  order,  approval,  bond or other paper or document,
unless  requested in writing so to do by Holders of Certificates  evidencing not
less than 25% of the Voting  Rights  allocated  to each  Class of  Certificates;
provided,  however,  that if the payment within a reasonable time to the Trustee
of the costs,  expenses or liabilities likely to be incurred by it in the making
of such investigation is, in the opinion of the Trustee,  not reasonably assured
to the Trustee by the  security  afforded to it by the terms of this  Agreement,
the Trustee may require  reasonable  indemnity against such expense or liability
as a condition to taking any such action;  the reasonable  expense of every such
investigation shall be paid by the Servicer in the event that such investigation
relates to an Event of Default  by the  Servicer,  if an Event of Default by the
Servicer  shall  have  occurred  and  is   continuing,   and  otherwise  by  the
Certificateholders requesting the investigation;
               (vi)  the  Trustee  may  execute  any of  the  trusts  or  powers
hereunder  or perform  any duties  hereunder  either  directly  or by or through
affiliates, agents or attorneys;
                                      -92-
               (vii) the  Trustee  shall not be required to expend its own funds
or otherwise  incur any  financial  liability in the  performance  of any of its
duties  hereunder  if it  shall  have  reasonable  grounds  for  believing  that
repayment  of such funds or adequate  indemnity  against  such  liability is not
assured to it; and
               (viii)  the  Trustee  shall  not be  liable  for any  loss on any
investment of funds pursuant to this Agreement.
          (b) All  rights of action  under  this  Agreement  or under any of the
Certificates,  enforceable  by the  Trustee,  may be  enforced by it without the
possession of any of the Certificates, or the production thereof at the trial or
other  proceeding  relating  thereto,  and any such suit,  action or  proceeding
instituted  by the  Trustee  shall be brought in its name for the benefit of all
the Holders of such Certificates, subject to the provisions of this Agreement.
     SECTION 9.03 TRUSTEE NOT LIABLE FOR CERTIFICATES OR MORTGAGE LOANS.
          The recitals  contained herein shall be taken as the statements of the
Depositor  or the  Servicer,  as the case may be,  and the  Trustee  assumes  no
responsibility for their correctness. The Trustee makes no representations as to
the  validity or  sufficiency  of this  Agreement,  the  Certificates  or of any
Mortgage Loan or related document.  The Trustee shall not be accountable for the
use or  application  by the  Depositor,  the Seller or the Servicer of any funds
paid to the  Depositor,  the Seller or the  Servicer in respect of the  Mortgage
Loans  or  deposited  in or  withdrawn  from  the  Certificate  Account  by  the
Depositor, the Seller or the Servicer.
     SECTION 9.04 TRUSTEE MAY OWN CERTIFICATES.
          The Trustee in its  individual  or any other  capacity  may become the
owner or  pledgee  of  Certificates  and may  transact  business  with the other
parties with the same rights as it would have if it were not the Trustee.
     SECTION 9.05 TRUSTEE'S COMPENSATION AND EXPENSES.
          As  compensation  for its  services  hereunder,  the Trustee  shall be
entitled to the Trustee  Float.  In the event that the  Servicer  fails to remit
amounts that it is required to remit to the Certificate Account hereunder on the
Business  Day prior to each  Distribution  Date  hereunder,  it shall pay to the
Trustee,  from its own funds,  an amount equal to the Trustee Float with respect
to such  Distribution  Date,  as  certified  in  writing  by the  Trustee to the
Servicer and agreed to by the  Servicer.  The Servicer  shall also pay, from its
own funds, the Trustee any additional  amounts as may be agreed upon between the
Trustee and the Servicer from time to time.  Any payment  hereunder  made by the
Servicer to the Trustee,  other than any amount to be paid from the  Certificate
Account  pursuant to this Section 9.05,  shall be paid from the  Servicer's  own
funds, without reimbursement from the Trust Fund therefor.
          The  Trustee  and any  director,  officer,  employee  or  agent of the
Trustee shall be indemnified by the Servicer and held harmless against any loss,
liability or expense (a) incurred in connection  with any legal action  relating
to  this  Agreement  or  the  Certificates,  or  the  performance  of any of the
Trustee's duties hereunder,  other than any loss,  liability or expense incurred
by reason of willful misfeasance,  bad faith or negligence in the performance of
any of the Trustee's duties hereunder or by reason of reckless  disregard of the
Trustee's  obligations and duties  hereunder and
                                      -93-
(b) resulting from the exercise of any power of attorney  granted by the Trustee
in accordance with this Agreement.  Such indemnity shall survive the termination
of this Agreement or the resignation or removal of the Trustee hereunder.
     SECTION 9.06 ELIGIBILITY REQUIREMENTS FOR TRUSTEE.
          The  Trustee  hereunder  shall  at  all  times  be  a  corporation  or
association  having its principal  office in a state and city  acceptable to the
Depositor and the Servicer and organized  and doing  business  under the laws of
such  state or the  United  States of  America,  authorized  under  such laws to
exercise   corporate  trust  powers,   having  ratings  on  its  long-term  debt
obligations at the time of such appointment in at least the third highest rating
category by both  Moody's and ▇▇▇▇ and ▇▇▇▇▇▇ or such lower  ratings as will not
cause  Moody's or ▇▇▇▇ and  ▇▇▇▇▇▇ to lower  their  then-current  ratings of the
Class A  Certificates,  having  a  combined  capital  and  surplus  of at  least
$50,000,000  and  subject  to  supervision  or  examination  by federal or state
authority.  If such corporation or association publishes reports of condition at
least  annually,  pursuant  to  law  or to the  requirements  of  the  aforesaid
supervising or examining  authority,  then for the purposes of this Section 9.06
the combined  capital and surplus of such  corporation or  association  shall be
deemed to be its  combined  capital  and surplus as set forth in its most recent
report of condition so published. In case at any time the Trustee shall cease to
be eligible in accordance  with the provisions of this Section 9.06, the Trustee
shall resign  immediately in the manner and with the effect specified in Section
9.07 hereof.
     SECTION 9.07 RESIGNATION AND REMOVAL OF TRUSTEE.
          The Trustee may at any time resign and be  discharged  from the trusts
hereby created by (a) giving written notice of resignation to the Depositor, the
Seller and the  Servicer  and by mailing  notice of  resignation  by first class
mail, postage prepaid, to the Certificateholders at their addresses appearing on
the  Certificate  Register  and,  so long  as the  Class  I-A  and  the  Class B
Certificates  are  outstanding,  to the Rating  Agencies,  not less than 60 days
before the date  specified in such notice when,  subject to Section  9.08,  such
resignation  is to take effect,  and (b)  acceptance  by a successor  trustee in
accordance  with Section 9.08  meeting the  qualifications  set forth in Section
9.06.  If no successor  trustee  shall have been so appointed  and have accepted
appointment  within 30 days after the giving of such notice of resignation,  the
resigning  Trustee may  petition  any court of  competent  jurisdiction  for the
appointment of a successor trustee.
          If at any time the Trustee  shall  cease to be eligible in  accordance
with the  provisions  of Section  9.06  hereof  and shall  fail to resign  after
written  request  thereto by the  Servicer,  or if at any time the Trustee shall
become incapable of acting,  or shall be adjudged a bankrupt or insolvent,  or a
receiver of the Trustee or of its  property  shall be  appointed,  or any public
officer  shall  take  charge or control of the  Trustee  or of its  property  or
affairs for the purpose of rehabilitation, conservation or liquidation or if the
Trustee breaches any of its obligations or representations  hereunder,  then the
Depositor,  with the consent of the  Servicer,  may remove the Trustee and, with
the consent of the Servicer,  appoint a successor trustee by written instrument,
in duplicate, one copy of which instrument shall be delivered to the Trustee and
one copy to the successor  trustee and, so long as the Class I-A and the Class B
Certificates  are outstanding,  to the Rating Agencies.  The Trustee may also be
removed at any time by the Holders of Certificates  evidencing not less than 50%
of the Voting Rights evidenced by the Certificates.
                                      -94-
          Any  resignation  or  removal  of the  Trustee  and  appointment  of a
successor  trustee  pursuant to any of the provisions of this Section 9.07 shall
become  effective upon  acceptance of  appointment  by the successor  trustee as
provided in Section 9.08 hereof.
     SECTION 9.08 SUCCESSOR TRUSTEE.
          If the Trustee resigns  pursuant to Section 9.07, the Depositor,  with
the consent of the Servicer,  shall appoint a successor  trustee that  satisfies
the requirements of Section 9.06. Any successor trustee appointed as provided in
Section 9.07 hereof shall execute,  acknowledge and deliver to the Depositor and
the  Servicer  and to its  predecessor  trustee  an  instrument  accepting  such
appointment   hereunder  and  thereupon  the   resignation  or  removal  of  the
predecessor  trustee shall become effective and such successor trustee,  without
any further  act,  deed or  conveyance,  shall  become fully vested with all the
rights,  powers, duties and obligations of its predecessor  hereunder,  with the
like effect as if  originally  named as trustee  herein.  The  Depositor and the
predecessor trustee shall execute and deliver such instruments and do such other
things as may  reasonably be required for more fully and  certainly  vesting and
confirming  in the  successor  trustee  all such  rights,  powers,  duties,  and
obligations.
          No  successor  trustee  shall accept  appointment  as provided in this
Section 9.08 unless at the time of such acceptance such successor  trustee shall
be eligible  under the provisions of Section 9.06 hereof and shall not adversely
affect the then current rating of the Certificates.
          Upon  acceptance of appointment by a successor  trustee as provided in
this Section  9.08,  the Servicer  shall mail notice of the  succession  of such
trustee  hereunder to all Holders of Certificates at their addresses as shown in
the Certificate  Register.  If the Servicer fails to mail such notice within ten
days after  acceptance of  appointment by the successor  trustee,  the successor
trustee shall cause such notice to be mailed at the expense of the Depositor.
     SECTION 9.09 MERGER OR CONSOLIDATION OF TRUSTEE.
          Any Person into which the Trustee may be merged or  converted  or with
which it may be consolidated or any Person resulting from any merger, conversion
or consolidation to which the Trustee shall be a party, or any Person succeeding
to the business of the Trustee, shall be the successor of the Trustee hereunder,
provided that such Person shall be eligible under the provisions of Section 9.06
hereof  without the  execution or filing of any paper or further act on the part
of any of the parties hereto, anything herein to the contrary notwithstanding.
     SECTION 9.10 APPOINTMENT OF CO-TRUSTEE OR SEPARATE TRUSTEE.
          Notwithstanding  any other provisions of this Agreement,  at any time,
for the purpose of meeting any legal  requirements of any  jurisdiction in which
any part of the Trust Fund or property  securing  any  Mortgage  Note may at the
time be located,  the Servicer  and the Trustee  acting  jointly  shall have the
power and shall  execute  and  deliver  all  instruments  to appoint one or more
Persons approved by the Trustee to act as co-trustee or co-trustees jointly with
the Trustee, or separate trustee or separate trustees, of all or any part of the
Trust Fund, and to vest in such Person or Persons,  in such capacity and for the
benefit of the applicable  Certificateholders,  such title to the Trust Fund, or
any part  thereof,  and,  subject to the other  provisions of this Section 9.10,
such  powers,  duties,  obligations,  rights and trusts as the  Servicer and the
Trustee may consider  necessary
                                      -95-
or desirable.  If the Servicer shall not have joined in such appointment  within
fifteen  days  after the  receipt by it of a request to do so, or in the case an
Event of Default shall have occurred and be continuing,  the Trustee alone shall
have the power to make such  appointment.  No  co-trustee  or  separate  trustee
hereunder  shall be  required  to meet the terms of  eligibility  as a successor
trustee  under  Section  9.06  and  no  notice  to   Certificateholders  of  the
appointment  of any  co-trustee  or separate  trustee  shall be  required  under
Section 9.08.
          Every separate  trustee and co-trustee  shall, to the extent permitted
by law, be appointed and act subject to the following provisions and conditions:
          (a) all rights,  powers,  duties and obligations  conferred or imposed
upon the Trustee,  except for any obligation of the Trustee under this Agreement
to advance funds on behalf of the  Servicer,  shall be conferred or imposed upon
and  exercised  or  performed  by the  Trustee  and  such  separate  trustee  or
co-trustee jointly (it being understood that such separate trustee or co-trustee
is not  authorized to act separately  without the Trustee  joining in such act),
except  to the  extent  that  under  any law of any  jurisdiction  in which  any
particular  act or acts are to be performed  by the Trustee  (whether as Trustee
hereunder or as successor to the Servicer),  the Trustee shall be incompetent or
unqualified  to perform such act or acts,  in which event such  rights,  powers,
duties and obligations  (including the holding of title to the Trust Fund or any
portion  thereof in any such  jurisdiction)  shall be  exercised  and  performed
singly by such separate  trustee or  co-trustee,  but solely at the direction of
the Trustee;
          (b) no trustee  hereunder shall be held personally liable by reason of
any act or omission of any other trustee hereunder; and
          (c) the Servicer and the Trustee acting jointly may at any time accept
the resignation of or remove any separate trustee or co-trustee.
          Any notice,  request or other  writing  given to the Trustee  shall be
deemed to have been given to each of the then separate trustees and co-trustees,
as  effectively  as if given to each of them.  Every  instrument  appointing any
separate  trustee or co-trustee shall refer to this Agreement and the conditions
of this Article IX. Each separate trustee and co-trustee, upon its acceptance of
the trusts conferred,  shall be vested with the estates or property specified in
its instrument of appointment, either jointly with the Trustee or separately, as
may be  provided  therein,  subject  to all the  provisions  of this  Agreement,
specifically including every provision of this Agreement relating to the conduct
of, affecting the liability of, or affording  protection to, the Trustee.  Every
such instrument  shall be filed with the Trustee and a copy thereof given to the
Servicer and the Depositor.
          Any separate  trustee or co-trustee  may, at any time,  constitute the
Trustee its agent or  attorney-in-fact,  with full power and  authority,  to the
extent not  prohibited  by law, to do any lawful act under or in respect of this
Agreement on its behalf and in its name.  If any separate  trustee or co-trustee
shall die, become incapable of acting, resign or be removed, all of its estates,
properties,  rights,  remedies  and trusts shall vest in and be exercised by the
Trustee,  to the extent  permitted by law,  without the  appointment of a new or
successor trustee.
                                      -96-
     SECTION 9.11 OFFICE OF THE TRUSTEE.
          The office of the  Trustee  for  purposes  of  receipt of notices  and
demands is the Corporate Trust Office.
     SECTION 9.12 TAX RETURNS.
          The  Servicer,  upon  request,  will furnish the Trustee with all such
information in the  possession of the Servicer as may be reasonably  required in
connection  with  the  preparation  by the  Trustee  of all tax and  information
returns of the Trust Fund, and the Trustee shall sign such returns. The Servicer
shall  indemnify the Trustee for all  reasonable  costs,  including  legal fees,
related to errors in such tax returns due to errors in  information  provided by
the Servicer.
                                    ARTICLE X
                                   TERMINATION
     SECTION 10.01  TERMINATION  UPON  LIQUIDATION OR REPURCHASE OF ALL MORTGAGE
LOANS.
          (a) The obligations and responsibilities of the Servicer,  the Seller,
the  Depositor  and the Trustee  created  hereby with  respect to the Trust Fund
created hereby shall terminate upon the earlier of:
               (i)  the  repurchase  by the  Servicer  at its  election,  of all
Mortgage  Loans and all  property  acquired  in  respect  of any  Mortgage  Loan
remaining in the Trust Fund, which repurchase right the Servicer may exercise at
its sole and exclusive  election as of any  Distribution  Date (such  applicable
Distribution Date being herein referred to as the "Optional  Termination  Date")
on or after the date on which the  aggregate  Principal  Balance of the Mortgage
Loans  at the  time of the  repurchase  is  less  than  or  equal  to 10% of the
aggregate  Principal  Balance  of the  Mortgage  Loans as of the  Cut-off  Date.
Notwithstanding the foregoing, the Servicer, will not exercise any such right on
any Optional  Termination  Date unless the  aggregate  Principal  Balance of the
Class  AR5  Mortgage  Loans at the time of  repurchase  is less than or equal to
1.00% of the aggregate  Principal  Balance of the Class AR5 Mortgage Loans as of
the Class AR5 Cut-off Date;
               (ii) the later of (i) twelve  months  after the  maturity  of the
last Mortgage Loan  remaining in the Trust Fund,  (ii) the  liquidation  (or any
advance with respect  thereto) of the last Mortgage Loan  remaining in the Trust
Fund and the  disposition  of all REO  Property  and (iii) the  distribution  to
Certificateholders of all amounts required to be distributed to them pursuant to
this Agreement; and
               (iii)  the  date  upon  which  all  Certificateholders   vote  to
terminate the Trust REMIC, REMIC I and REMIC II.
          In no event  shall  the  trust  created  hereby  continue  beyond  the
expiration of 21 years from the death of the last survivor of the descendants of
▇▇. ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇,  former Ambassador of the United States to Great Britain,
living on the date of execution of this Agreement.
                                      -97-
          The Mortgage Loan Repurchase  Price for any such Optional  Termination
of the Trust  Fund  shall be equal to the  aggregate  Principal  Balance  of the
Mortgage  Loans as of the date of  repurchase,  together with accrued and unpaid
interest  thereon  from the date to which such  interest was paid or advanced at
the sum of the  applicable  Net Mortgage Rate or Class AR5 Net Mortgage Rate, as
applicable, with respect to each Mortgage Loan through the last day of the month
of such  repurchase,  plus any sums on account of such  Mortgage  Loan that have
been  advanced by the Servicer and are  reimbursable  to the Servicer  hereunder
(including  the Principal  Balance of each Mortgage Loan that was secured by any
REO Property);  PROVIDED,  HOWEVER,  that if the Servicer  shall so choose,  the
Servicer may remit the Mortgage Loan Repurchase Price net of advances that would
otherwise be reimbursable to the Servicer and the Servicer would have no further
entitlement to reimbursement for such advances. The Trustee shall give notice to
the  Rating  Agencies  of the  Servicer's  election  to  purchase  the Class AR5
Mortgage Loans pursuant to this Section 10.01.
          (b) The Servicer shall also have the right, on any  Distribution  Date
on which the aggregate Principal Balance of the Class AR5 Mortgage Loans is less
than or equal to 1.00% of the  aggregate  Principal  Balance  of the  Class  AR5
Mortgage  Loans as of the Class AR5 Cut-off Date to purchase the assets of REMIC
I at a price equal to the aggregate  Principal Balance of the Class AR5 Mortgage
Loans as of the date of  repurchase,  together with accrued and unpaid  interest
thereon from the date to which such  interest was paid or advanced at the sum of
the  applicable  Class AR5 Net Mortgage  Rate with respect to each Mortgage Loan
through the last day of the month of such  repurchase,  plus any sums on account
of such Class AR5 Mortgage  Loan that have been advanced by the Servicer and are
reimbursable to the Servicer hereunder or, in the case of any REO Property,  the
fair market value of the REO Property,  if less; PROVIDED,  HOWEVER, that if the
Servicer  shall so choose,  the Servicer may remit the Mortgage Loan  Repurchase
Price net of advances that would  otherwise be  reimbursable to the Servicer and
the  Servicer  would  have no  further  entitlement  to  reimbursement  for such
advances (a "Class AR5 Optional Termination Date").
     SECTION 10.02 PROCEDURE UPON OPTIONAL OR OTHER FINAL TERMINATION.
          (a)  In  case  of any  Optional  Termination  or  Class  AR5  Optional
Termination, pursuant to Section 10.01, the Servicer shall, at least twenty days
prior to the date  notice  is to be mailed  to the  affected  Certificateholders
notify  the  Trustee of such  Optional  Termination  Date or Class AR5  Optional
Termination Date, as applicable.
          (b) Any  repurchase  of the  Mortgage  Loans  or the  REMIC I  Regular
Interests  held as  assets  of  REMIC  II by the  Servicer  shall  be made on an
Optional Termination Date or Class AR5 Optional Termination Date, as applicable,
by deposit of the applicable  repurchase price into the Certificate  Account, as
applicable,  before the Distribution  Date on which such repurchase is effected.
Upon  receipt  by the  Trustee  of an  Officers'  Certificate  of  the  Servicer
certifying  as to the  deposit of such  repurchase  price  into the  Certificate
Account,  the Servicer  shall  prepare and the Trustee and each  co-trustee  and
separate trustee, if any, then acting as such under this Agreement,  shall, upon
request  and at the  expense  of the  Servicer  execute  and  deliver  all  such
instruments of transfer or assignment,  in each case without recourse,  as shall
be necessary,  to vest title in the Servicer in the Mortgage  Loans or assets of
REMIC I so  repurchased  and shall  transfer  or  deliver  to the  Servicer  the
repurchased Mortgage Loans or assets. Any distributions on the Mortgage Loans or
assets of REMIC I received by the Trustee  subsequent to (or with respect to any
period  subsequent  to) the  Optional  Termination  Date or Class  AR5  Optional
Termination Date shall be promptly remitted by it to the Servicer.
                                      -98-
          (c) Notice of the Distribution Date on which the Servicer  anticipates
that the final distribution shall be made (whether upon Optional  Termination or
otherwise) or notice of the Class AR5 Optional  Termination Date, shall be given
promptly  by the  Servicer to the Trustee and by the Trustee by first class mail
to Holders of the affected Certificates.  Such notice shall be mailed no earlier
than the 15th day and not  later  than  the  10th  day  preceding  the  Optional
Termination  Date,  Class  AR5  Optional  Termination  Date  or  date  of  final
distribution, as the case may be. Such notice shall specify (i) the Distribution
Date upon which final  distribution  on the affected  Certificates  will be made
upon  presentation  and surrender of such  Certificates  at the office or agency
therein  designated,  (ii) the amount of such final  distribution and (iii) that
the  Record  Date  otherwise   applicable  to  such  Distribution  Date  is  not
applicable, such distribution being made only upon presentation and surrender of
such  Certificates  at the office or agency  maintained  for such  purposes (the
address of which shall be set forth in such notice).
          (d) In the  event  that any  Certificateholders  shall  not  surrender
Certificates for cancellation  within six months after the date specified in the
above mentioned  written notice,  the Trustee shall give a second written notice
to the remaining such  Certificateholders  to surrender their  Certificates  for
cancellation and receive the final distribution with respect thereto.  If within
six months  after the second  notice  all the  Certificates  shall not have been
surrendered for  cancellation,  the Trustee may take  appropriate  steps, or may
appoint  an  agent  to  take   appropriate   steps,  to  contact  the  remaining
Certificateholders  concerning  surrender  of their  Certificates,  and the cost
thereof shall be paid out of the funds and other assets which remain  subject to
the Trust Fund.
     SECTION 10.03 ADDITIONAL TERMINATION REQUIREMENTS.
          (a) In the event the Servicer  exercises its purchase  option pursuant
to Section  10.01 or the  Certificateholders  vote to terminate the Trust REMIC,
REMIC I and REMIC II pursuant to Section 10.01(a)(iii), the Trust REMIC shall be
terminated in accordance with the following additional requirements,  unless the
Trustee has received an Opinion of Counsel to the effect that the failure of the
Trust  REMIC,  REMIC I and  REMIC II to  comply  with the  requirements  of this
Section  will  not (i)  result  in the  imposition  of  taxes  on a  "prohibited
transaction"  of the Trust REMIC,  REMIC I and REMIC II, as described in Section
860F of the Code, or (ii) cause the Trust REMIC, REMIC I and REMIC II to fail to
qualify as a REMIC at any time that any Certificates are outstanding:
                    (A) within 90 days prior to the final  Distribution Date set
     forth in the notice given by the Servicer under Section  10.02,  the Holder
     of the Class R and Class I-R  Certificates  shall  adopt a plan of complete
     liquidation of the Trust REMIC,  REMIC I and REMIC II and specify the first
     day of the applicable 90-day  liquidation period in a statement attached to
     the Trust Fund's final tax return pursuant to Treasury  Regulations Section
     1.860F-1, and satisfy (or cause to be satisfied) all of the requirements of
     a qualified liquidation under the REMIC Provisions; and
                    (B) at or after  the time of  adoption  of any such  plan of
     complete  liquidation for the Trust REMIC, REMIC I and REMIC II at or prior
     to the final Distribution Date, the Trustee shall sell all of the assets of
     the Trust Fund to the Servicer  for cash;  provided,  however,  that in the
     event that a calendar  quarter  ends after the time of  adoption  of such a
     plan of complete  liquidation but prior to the final Distribution Date, the
                                      -99-
     Trustee  shall not sell any of the  assets of the Trust  Fund  prior to the
     close of that calendar quarter.
          (b) By its  acceptance of a Class R Certificate,  the Holders  thereof
hereby agree to adopt such a plan of complete liquidation and to take such other
action in connection  therewith as may be  reasonably  required to liquidate and
otherwise terminate the Trust REMIC, REMIC I and REMIC II.
                                   ARTICLE XI
                            MISCELLANEOUS PROVISIONS
     SECTION 11.01 AMENDMENT.
          (a) This  Agreement may be amended from time to time by the Depositor,
the  Servicer,  the Seller and the  Trustee  without  the  consent of any of the
Certificateholders,
               (i) to cure any ambiguity,
               (ii) to correct or supplement any  provisions  herein that may be
inconsistent with any other provisions herein,
               (iii) to modify,  eliminate  or add to any of its  provisions  to
such extent as shall be necessary or desirable to maintain the  qualification of
the  Trust  REMIC,  REMIC  I or  REMIC  II as a  REMIC  at all  times  that  any
Certificate is outstanding or to avoid or minimize the risk of the imposition of
any tax on the Trust Fund pursuant to the Code that would be a claim against the
Trust Fund,  provided that the Trustee has received an Opinion of Counsel to the
effect  that  (A) such  action  is  necessary  or  desirable  to  maintain  such
qualification or to avoid or minimize the risk of the imposition of any such tax
and (B) such action  will not  adversely  affect the status of the Trust  REMIC,
REMIC I or REMIC II as a REMIC or adversely  affect in any material  respect the
interests of any Certificateholder,
               (iv) to make any other  provisions  with  respect  to  matters or
questions arising under this Agreement that are not materially inconsistent with
the provisions of this Agreement,  provided that such action shall not adversely
affect in any material respect the interests of any  Certificateholder  or cause
an Adverse REMIC Event, or
               (v) To add  appropriate  restrictions  and  legends to any of the
Class A Certificates.
          (b) This  Agreement may be amended from time to time by the Depositor,
the  Servicer,  the Seller and the  Trustee  with the  consent of the Holders of
Certificates  evidencing,  in the aggregate, not less than 66-2/3% of the Voting
Rights of each Class of Certificates affected by such amendment, for the purpose
of adding any provisions to or changing in any manner or eliminating  any of the
provisions  of this  Agreement  or of  modifying in any manner the rights of the
Holders of the Certificates;  provided,  however, that no such amendment may (i)
reduce in any manner the amount of,  delay the timing of or change the manner in
which payments  received on or with respect to Mortgage Loans are required to be
distributed with respect to any Certificate without the consent of the Holder of
such Certificate,  (ii) reduce the aforesaid  percentages of Voting Rights,  the
holders
                                     -100-
of which are  required to consent to any such  amendment  without the consent of
100% of the Holders of Certificates of the Class affected thereby,  (iii) change
the  percentage  of the  Principal  Balance of the Mortgage  Loans  specified in
Section 10.01(a)(i)  relating to optional  termination of the Trust Fund without
the consent of 100% of the Holders of  Certificates,  (iv) modify the provisions
of this Section  11.01  amendment  without the consent of 100% of the Holders of
Certificates,  or (v)  terminate  this  Agreement  or  the  Trust  Fund  created
hereunder other than as provided in Article X hereof without the consent of 100%
of the Holders of  Certificates.  It shall not be  necessary  for the consent of
Certificateholders  under this  Section to approve  the  particular  form of any
proposed amendment, but it shall be sufficient if such consent shall approve the
substance  thereof.  The manner of obtaining such consents and of evidencing the
authorization of the execution thereof by Certificateholders shall be subject to
such reasonable regulations as the Trustee may prescribe.
          (c) Promptly  after the execution of any amendment to this  Agreement,
the  Trustee  shall  furnish  written  notification  of the  substance  of  such
amendment to each Certificateholder and, if any Class I-A or Class B Certificate
is outstanding, to the Rating Agencies.
          (d) Prior to the  execution of any  amendment to this  Agreement,  the
Trustee  shall  receive  an  Opinion  of  Counsel  that  any such  amendment  is
authorized  by and  permitted  hereunder  and that it will not cause an  Adverse
REMIC Event.
     SECTION 11.02 RECORDATION OF AGREEMENT; COUNTERPARTS.
          (a) This Agreement is subject to recordation in all appropriate public
offices  for real  property  records  in all the  counties  or other  comparable
jurisdictions in which any or all of the Mortgaged Properties are situated,  and
in any other appropriate public recording office or elsewhere. Such recordation,
if any,  shall be effected by the  Servicer at its expense on  direction  of the
Trustee,  but only upon  direction of the Trustee  accompanied  by an Opinion of
Counsel to the effect that such recordation  materially and beneficially affects
the interests of the Certificateholders of the Trust Fund.
          (b) For the purpose of facilitating  the recordation of this Agreement
as herein  provided  and for other  purposes,  this  Agreement  may be  executed
simultaneously in any number of counterparts,  each of which  counterparts shall
be deemed to be an original,  and such counterparts shall constitute but one and
the same instrument.
     SECTION 11.03 GOVERNING LAW.
          THIS AGREEMENT  SHALL BE CONSTRUED IN ACCORDANCE  WITH AND GOVERNED BY
THE SUBSTANTIVE  LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS MADE AND
TO BE  PERFORMED  IN THE  STATE  OF NEW  YORK AND THE  OBLIGATIONS,  RIGHTS  AND
REMEDIES OF THE PARTIES HERETO AND THE CERTIFICATEHOLDERS SHALL BE DETERMINED IN
ACCORDANCE WITH SUCH LAWS.
     SECTION 11.04 INTENTION OF PARTIES.
          (a)  It is the  express  intent  of the  Depositor,  the  Seller,  the
Servicer  and the Trustee  that the  conveyance  by the Seller to the  Depositor
pursuant to the Mortgage  Loan  Purchase  Agreement  and the  conveyance  by the
Depositor  to the Trustee  and by the Seller to the  Trustee as
                                     -101-
provided  for in Section 2.01 of each of the  Seller's  and  ▇▇▇▇▇▇▇▇▇'s  right,
title and  interest in and to the  Mortgage  Loans be, and be  construed  as, an
absolute sale and assignment by the Seller to the Depositor and by the Depositor
to the Trustee of the Mortgage Loans for the benefit of the  Certificateholders.
Further,  it is not intended that either  conveyance be deemed to be a pledge of
the Mortgage by the Seller to the  Depositor or by the  Depositor to the Trustee
to secure a debt or other  obligation.  However,  in the event that the Mortgage
Loans are held to be  property  of the  Seller or the  Depositor,  or if for any
reason the Mortgage Loan Purchase  Agreement or this Agreement is held or deemed
to create a security  interest in the Mortgage  Loans,  then it is intended that
(i) this Agreement  shall also be deemed to be a security  agreement  within the
meaning of  Articles  8 and 9 of the New York  Uniform  Commercial  Code and the
Uniform  Commercial  Code  of  any  other  applicable  jurisdiction;   (ii)  the
conveyances  provided  for in Section  2.01 shall be deemed to be a grant by the
Seller and the Depositor to the Trustee on behalf of the Certificateholders,  to
secure  payment in full of the  Secured  Obligations  (as defined  below),  of a
security  interest in all of the Seller's and the Depositor's  right  (including
the power to convey title  thereto),  title and  interest,  whether now owned or
hereafter acquired, in and to the Mortgage Loans,  including the Mortgage Notes,
the Mortgages,  any related  insurance  policies and all other  documents in the
related Mortgage Files, and all accounts,  general  intangibles,  chattel paper,
instruments, documents, money, deposit accounts, certificates of deposit, goods,
letters of credit,  advices of credit and investment  property consisting of the
Trust Fund,  arising from or relating to (A) the Mortgage Loans,  including with
respect to each Mortgage Loan, the Mortgage Note and related  Mortgage,  and all
other  documents in the related  Mortgage  Files,  and including any Replacement
Mortgage Loans; (B) pool insurance  policies,  hazard insurance policies and any
bankruptcy  bond relating to the foregoing,  if applicable;  (C) the Certificate
Account;  (D) the Custodial  Account;  (E) all amounts payable after the Cut-off
Date to the holders of the Mortgage Loans in accordance  with the terms thereof;
(F) all income, payments, proceeds and products of the conversion,  voluntary or
involuntary,  of the  foregoing  into  cash,  instruments,  securities  or other
property,  including  without  limitation  all amounts from time to time held or
invested in the Certificate Account,  whether in the form of cash,  instruments,
securities or other property;  and (G) all cash and non-cash  proceeds of any of
the foregoing; (iii) the possession or control by the Trustee or any other agent
of the Trustee of Mortgage  Notes or such other items of property as  constitute
instruments,  money,  documents,  advices of credit,  letters of credit,  goods,
certificated  securities  or chattel  paper shall be deemed to be  possession or
control by the secured  party,  or  possession  or control by a  purchaser,  for
purposes of perfecting the security interest pursuant to the Uniform  Commercial
Code (including, without limitation,  Sections 9-305 or 9-115 thereof); and (iv)
notifications to persons holding such property, and acknowledgments, receipts or
confirmations from persons holding such property,  shall be deemed notifications
to,   or   acknowledgments,   receipts   or   confirmations   from,   securities
intermediaries,  bailees or agents of, or persons  holding for, the Trustee,  as
applicable,   for  the  purpose  of  perfecting  such  security  interest  under
applicable   law.   "Secured   Obligations"   means  (i)  the   rights  of  each
Certificateholder  to be paid any amount owed to it under this  Agreement,  (ii)
all other  obligations of the Seller and the Depositor  under this Agreement and
the   Mortgage   Loan   Purchase   Agreement   and   (iii)   the  right  of  the
Certificateholders to the Mortgage Loans.
          (b) The Seller and the Depositor,  and, at the Depositor's  direction,
the  Servicer  and the  Trustee,  shall,  to the  extent  consistent  with  this
Agreement,  take such reasonable  actions as may be necessary to ensure that, if
this Agreement  were deemed to create a security  interest in the Mortgage Loans
and the other Trust Fund property  described above, such security interest would
be deemed to be a perfected  security  interest of first priority as applicable.
The Servicer shall file, at its expense,  all filings  necessary to maintain the
effectiveness  of any original  filings  necessary under the
                                     -102-
Uniform  Commercial  Code  as in  effect  in any  jurisdiction  to  perfect  the
Trustee's security interest in or lien on the Mortgage Loans,  including without
limitation (i)  continuation  statements,  (ii) such other  statements as may be
occasioned  by any transfer of any interest of the Servicer or the  Depositor in
any Mortgage Loan; and filings necessary as a result in any change in the UCC.
     SECTION 11.05 NOTICES.
          In addition to other notices provided under this Agreement, so long as
any Class I-A or Class B Certificate  is  outstanding,  the Trustee shall notify
the Rating  Agencies in writing:  (a) of any  substitution of any Mortgage Loan;
(b) of the final  payment of any amounts owing to a Class of  Certificates;  (c)
any Event of Default  under this  Agreement;  and (d) in the event any  Mortgage
Loan is repurchased in accordance with this Agreement.
          All  directions,  demands  and notices  hereunder  shall be in writing
(except where also required to be given  telephonically)  and shall be deemed to
have been duly  given when  received  (i) in the case of the  Depositor,  Credit
Suisse First Boston Mortgage  Securities Corp., ▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇▇
▇▇▇▇ ▇▇▇▇▇,  Attention:  President;  (ii) in the case of the Trustee,  Bank One,
National  Association,  ▇ ▇▇▇▇ ▇▇▇  ▇▇▇▇▇,  ▇▇▇▇▇  ▇▇▇-▇▇▇▇,  ▇▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇
▇▇▇▇▇-0126,  Attention:  Global  trust  Services  or such  other  address as may
hereafter be furnished to the Depositor,  the Seller and the Servicer in writing
by the Trustee;  (iv) in the case of the Seller or Servicer,  Washington  Mutual
Bank, FA, ▇▇▇ ▇. ▇▇▇▇ ▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇,  Attention:  ▇▇▇▇ ▇.
▇▇▇▇▇▇▇  and a copy to ▇▇▇▇▇  ▇▇▇▇▇▇▇  ▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇▇▇▇,  ▇▇▇▇▇▇▇▇▇▇  ▇▇▇▇▇,
Attention:  ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ (with a copy to ▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇,
▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, Attention:  ▇▇▇ ▇. ▇▇▇▇▇▇▇,  General Counsel); and (iv) in the
case of the Rating Agencies,  ▇▇▇▇▇'▇ Investors  Service,  ▇▇ ▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇
▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇,  Attention:  Mortgage-Backed  Securities  Rating Group and
Standard & Poor's,  ▇▇ ▇▇▇▇▇  ▇▇▇▇▇▇,  ▇▇▇▇  ▇▇▇▇▇,  ▇▇▇ ▇▇▇▇,  ▇▇▇ ▇▇▇▇  ▇▇▇▇▇.
Notices given by telecopy shall be deemed  received when request is confirmed by
telephone.  Notices of default are also required to be given by registered mail.
Notices to  Certificateholders  shall be deemed given when  mailed,  first class
postage prepaid.
     SECTION 11.06 SEVERABILITY OF PROVISIONS.
          If any one or more of the covenants,  agreements,  provisions or terms
of this Agreement  shall be for any reason  whatsoever  held invalid,  then such
covenants,  agreements,  provisions or terms shall be deemed  severable from the
remaining covenants, agreements, provisions or terms of this Agreement and shall
in no way affect the validity or  enforceability of the other provisions of this
Agreement or of the Certificates or the rights of the Holders thereof.
     SECTION 11.07 LIMITATION ON RIGHTS OF CERTIFICATEHOLDERS.
          The death or incapacity of any Certificateholder  shall not operate to
terminate this Agreement or the Trust Fund, nor entitle such Certificateholder's
legal  representative  or heirs to claim an  accounting or to take any action or
commence any  proceeding  in any court for a petition or winding up of the Trust
Fund, or otherwise affect the rights, obligations and liabilities of the parties
hereto or any of them.
          No Certificateholder  shall have any right to vote (except as provided
herein) or in any manner  otherwise  control the operation and management of the
Trust Fund, or the obligations
                                     -103-
of the parties  hereto,  nor shall anything herein set forth or contained in the
terms   of   the   Certificates   be   construed   so  as  to   constitute   the
Certificateholders  from time to time as partners or members of an  association;
nor shall any  Certificateholder  be under any  liability  to any third party by
reason of any action  taken by the  parties to this  Agreement  pursuant  to any
provision hereof.
          No  Certificateholder  shall  have any right by virtue or by  availing
itself of any  provisions  of this  Agreement to institute  any suit,  action or
proceeding in equity or at law upon or under or with respect to this  Agreement,
unless such Holder  previously  shall have given to the Trustee a written notice
of an Event of Default and of the continuance  thereof,  as provided herein, and
unless the Holders of  Certificates  evidencing  not less than 25% of the Voting
Rights evidenced by the  Certificates  shall also have made written request upon
the Trustee to institute  such  action,  suit or  proceeding  in its own name as
Trustee  hereunder  and  shall  have  offered  to the  Trustee  such  reasonable
indemnity as it may require against the costs,  expenses,  and liabilities to be
incurred  therein or  thereby  shall have  given its  written  consent,  and the
Trustee,  for 60 days after its  receipt of such  notice,  request  and offer of
indemnity, shall have neglected or refused to institute any such action, suit or
proceeding;  it being understood and intended, and being expressly covenanted by
each Certificateholder with every other  Certificateholder and the Trustee, that
no one or more  Holders  of  Certificates  shall  have any  right in any  manner
whatever by virtue or by availing itself or themselves of any provisions of this
Agreement to affect, disturb or prejudice the rights of the Holders of any other
of the Certificates,  or to obtain or seek to obtain priority over or preference
to any other such Holder or to enforce any right under this Agreement, except in
the manner herein provided and for the common benefit of all Certificateholders.
For the protection and enforcement of the provisions of this Section 11.07, each
and every  Certificateholder and the Trustee shall be entitled to such relief as
can be given either at law or in equity.
     SECTION 11.08 CERTIFICATES NONASSESSABLE AND FULLY PAID.
          It is the intention of the Depositor that Certificateholders shall not
be personally  liable for  obligations of the Trust Fund,  that the interests in
the Trust Fund  represented by the Certificates  shall be nonassessable  for any
reason whatsoever, and that the Certificates, upon due authentication thereof by
the Trustee pursuant to this Agreement, are and shall be deemed fully paid.
                                     -104-
          IN WITNESS WHEREOF,  the Depositor,  the Servicer and the Trustee have
caused their names to be signed hereto by their  respective  officers  thereunto
duly authorized all as of the 6th day of December, 2001.
                                   CREDIT SUISSE FIRST BOSTON MORTGAGE
                                     SECURITIES CORP., as Depositor
                                   By:
                                       -----------------------------------------
                                       Name:    ▇▇▇▇ ▇. ▇▇▇▇▇▇▇
                                       Title:   Vice President
                                   WASHINGTON MUTUAL BANK, FA,
                                     as Seller and Servicer
                                   By:
                                       -----------------------------------------
                                       Name:
                                       Title:
                                   BANK ONE, NATIONAL ASSOCIATION,
                                     not in its individual capacity, but solely
                                     as Trustee
                                   By:
                                       -----------------------------------------
                                       Name:    ▇▇▇▇▇▇▇ ▇▇▇▇▇▇
                                       Title:
STATE OF ILLINOIS          )
                           :  ss.:
COUNTY OF                  )
          ---------------
          On this    th day of December, 2001, before  me,  personally  appeared
                  ---
                         , known to me to be a                           of Bank
-------------------------                      -------------------------
One,  National  Association,  the national  association that executed the within
instrument,  and also known to me to be the person who  executed it on behalf of
said national association, and acknowledged to me that such national association
executed the within instrument.
          IN  WITNESS  WHEREOF,  I have  hereunto  set my hand  and  affixed  my
official seal the day and year in this certificate first above written.
                                  ----------------------------------------------
                                  Notary Public
[NOTARIAL SEAL]
STATE OF NEW YORK     )
                      :  ss.:
COUNTY OF NEW YORK    )
          On the     th day of December 2001,  before me,  personally   appeared
                 ----
▇▇▇▇ ▇.  ▇▇▇▇▇▇▇,  known to me to be a Vice  President  of Credit  Suisse  First
Boston Mortgage  Securities  Corp.,  one of the  corporations  that executed the
within  instrument  and also  known to me to be the person  who  executed  it on
behalf  of  said  corporation,  and  acknowledged  to me that  such  corporation
executed the within instrument.
          IN  WITNESS  WHEREOF,  I have  hereunto  set my hand  and  affixed  my
official seal the day and year in this certificate first above written.
                                  ----------------------------------------------
                                  Notary Public
[NOTARIAL SEAL]
STATE OF WASHINGTON        )
                           :  ss.:
COUNTY OF                  )
          -------------
          On the     th day of December, 2001, before me, a Notary Public in and
                 ----
for said State,  personally  appeared  ▇▇▇▇▇▇▇  ▇▇▇▇▇▇,  known to me to be a the
                          of Washington Mutual Bank, FA, the federally chartered
-------------------------
savings association, that executed the within instrument and also known to me to
be the person who  executed it on behalf of said bank,  and  acknowledged  to me
that such bank executed the within instrument.
          IN  WITNESS  WHEREOF,  I have  hereunto  set my hand  and  affixed  my
official seal the day and year in this certificate first above written.
                                  ----------------------------------------------
                                  Notary Public
[NOTARIAL SEAL]
                                    EXHIBIT A
                           FORM OF CLASS A CERTIFICATE
THIS  CERTIFICATE  HAS NOT BEEN AND WILL NOT BE REGISTERED  UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR THE SECURITIES LAWS OF ANY STATE AND MAY
NOT BE RESOLD OR  TRANSFERRED  UNLESS IT IS REGISTERED  PURSUANT TO SUCH ACT AND
LAWS OR IS SOLD OR TRANSFERRED IN TRANSACTIONS THAT ARE EXEMPT FROM REGISTRATION
UNDER SUCH ACT AND UNDER  APPLICABLE  STATE LAW AND IS TRANSFERRED IN ACCORDANCE
WITH THE PROVISIONS OF SECTION 6.02 OF THE AGREEMENT REFERRED TO HEREIN.
NO TRANSFER OF THIS CERTIFICATE MAY BE MADE TO AN EMPLOYEE BENEFIT OR OTHER PLAN
SUBJECT TO THE  EMPLOYEE  RETIREMENT  INCOME  SECURITY  ACT OF 1974,  AS AMENDED
("ERISA"), OR SECTION 4975 OF THE CODE.
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE  IS A "REGULAR
INTEREST"  IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT" AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE CODE.
THIS  CERTIFICATE  DOES NOT  REPRESENT  AN INTEREST IN OR  OBLIGATION  OF CREDIT
SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP., WASHINGTON MUTUAL BANK, FA OR THE
TRUSTEE  REFERRED TO BELOW, OR OF ANY OF THEIR  AFFILIATES.  THIS CERTIFICATE IS
NOT GUARANTEED OR INSURED BY ANY GOVERNMENT AGENCY OR INSTRUMENTALITY.
                                      A-1
                           WASHINGTON MUTUAL BANK, FA
                    MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
               SERIES 1999-WM4, CLASS A-[1][2][3[4][5][6[7][8][9]
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of fixed-rate and adjustable-rate, mortgage loans secured by first liens on one-
to- four-family  residential  real properties and certain other property held in
trust transferred by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
CUSIP                           $           Initial Aggregate Class A-[1] [2]
      --------                   -------    [3] [4] [5][6][7][8] [9] Certificate
                                            Principal Balance
Certificate No. A-[1], [2],     $           Initial Certificate Principal
[3],[4][5][6][7][8][9]           -------    Balance Of This Certificate
                      ---
First Distribution Date:                    Scheduled Final Distribution
January 19, 2000                            Date: [   ]
          THIS CERTIFIES THAT CEDE & CO. is the registered owner of a beneficial
interest in the Trust Fund referred to below  consisting of a pool of fixed-rate
and  adjustable-rate   mortgage  loans  secured  by  first  liens  on  one-  to-
four-family residential real properties (the "Mortgage Loans") and certain other
property  held in trust  transferred  to the Trust Fund by Credit  Suisse  First
Boston  Mortgage  Securities  Corp.  (the  "Depositor"),   and  certain  related
property.  The Trust Fund was created  pursuant  to the  Pooling  and  Servicing
Agreement, dated as of December 1, 1999 (the "Agreement"),  among the Depositor,
Bank One, National Association,  as trustee (the "Trustee",  which term includes
any successor  entity under the Agreement) and Washington  Mutual Bank,  FA., as
seller and servicer,  a summary of certain of the pertinent  provisions of which
is set forth  herein.  This  Certificate  is issued  under and is subject to the
terms, provisions and conditions of the Agreement, to which Agreement the Holder
of this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
1999-WM4 (the "Certificates"),  which is comprised of the following ten Classes:
Class A-1,  Class A-2,  Class A-3,  Class A-4,  Class A-5, Class A-6, Class A-7,
Class A-8,  Class A-9 and Class R. Reference is hereby made to the Agreement for
a statement of the respective rights thereunder of the Depositor and the Trustee
and the Holders of the  Certificates  and the terms upon which the  Certificates
are authenticated and delivered.  This Certificate represents an interest in the
Trust Fund,  which Trust Fund consists of, among other things,  (i) the Mortgage
Loans and all  distributions  thereon  payable  after the Cut-off  Date,  net of
certain  amounts in accordance  with the provisions of the  Agreement,  (ii) REO
Property,  (iii) the  Certificate  Account  and the  Custodial  Account  and all
amounts  deposited  therein  pursuant  to  the  applicable   provisions  of  the
Agreement,  net of any  investment  earnings  thereon,  (iv) the interest of the
Trust Fund in any insurance policies with respect to the Mortgage Loans, (v) the
rights of the  Depositor  assigned to the Trustee  pursuant to Sections 2.01 and
3.01 of the  Agreement,  and (vi) all proceeds of the  conversion,  voluntary or
involuntary, of any of the foregoing into cash or other liquid property.
                                      A-2
          This Class A Certificate represents a Percentage Interest equal to the
Initial Certificate Principal Balance of this Certificate divided by the Initial
Certificate Principal Balance of the Class A-[ ] Certificates, both as set forth
above.
          The Trustee shall  distribute  from the  Certificate  Account,  to the
extent of available  funds, on the 19th day of each month (each, a "Distribution
Date"), or if such 19th day is not a Business Day, the next succeeding  Business
Day, to the Person in whose name this  Certificate is registered at the close of
business on the last Business Day of the month  immediately  preceding the month
of such distribution  (each, a "Record Date"),  from the Available  Distribution
Amount in an amount equal to the product of the Percentage Interest evidenced by
this Certificate and the amount of interest and principal, if any required to be
distributed to the Class A-[ ] Certificates on such Distribution Date.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          Distributions on this Certificate will be made by the Trustee by check
mailed to the  address  of the Holder  hereof  entitled  thereto at the  address
appearing  in the  Certificate  Register or, if such Holder holds one or more of
this Class of  Certificates  with an  aggregate  initial  Certificate  Principal
Balance of at least $2,500,000 or all of the Certificates of this Class, by wire
transfer in immediately available funds to the account of such Certificateholder
designated  in writing to the Trustee at least five  Business  Days prior to the
applicable  Record Date.  Notwithstanding  the above, the final  distribution on
this  Certificate  will be made after due notice of the  pendency  of such final
distribution and only upon presentation and surrender of this Certificate at the
office or agency designated in such notice.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this  Certificate.  The  Agreement  also  permits the  Depositor,  the
Servicer,  the Seller and the Trustee to amend certain terms and  conditions set
forth in the Agreement  without the consent of Holders of the  Certificates.  At
any time  that any of the  Class of  Certificates  are  outstanding,  99% of all
Voting Rights will be allocated to the Holders of the  Certificates  (other than
the Class R Certificates),  in proportion to their then outstanding  Certificate
Principal  Balances  and 1.00% of all Voting  Rights  will be  allocated  to the
Holders of the Class R Certificates.
                                      A-3
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          The Class A Certificates  will be issued in fully  registered  form in
minimum  denominations of $100,000 Certificate Principal Balance and in integral
multiples of $1,000 in excess of such amount.  As provided in the  Agreement and
subject  to  certain   limitations   therein  set  forth,  this  Certificate  is
exchangeable  for  one or  more  new  Certificates  of  the  same  Class  and of
authorized  denominations  evidencing  a like  aggregate  Certificate  Principal
Balance, as requested by the Holder surrendering the same.
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
          The  obligations  and  responsibilities  of the Servicer,  the Seller,
Depositor  and the Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the Trust Fund of all remaining
Mortgage  Loans and all  property  acquired in respect of such  Mortgage  Loans,
thereby effecting early retirement of the Certificates,  (b) twelve months after
the maturity or other  liquidation (or any advance with respect  thereto) of the
last  Mortgage  Loan  remaining  in the Trust  Fund and the  disposition  of all
property  acquired  upon  foreclosure  or deed in  lieu  of  foreclosure  of any
Mortgage  Loan or (c) the agreement by all  Certificateholders  to terminate the
Trust REMIC,  REMIC I and REMIC II. As provided in the  Agreement,  the right to
purchase all Mortgage  Loans  pursuant to clause (a) above shall be  conditioned
upon the unpaid  Principal  Balances of such Mortgage  Loans, at the time of any
such  repurchase,  aggregating  less  than  or  equal  to 10%  of the  aggregate
Principal Balances thereof as of the Cut-off Date.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                      A-4
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                        BANK ONE, NATIONAL ASSOCIATION
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
      ---------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
    -------------------------------
    Authorized Officer
                                      A-5
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                      A-6
                                   EXHIBIT A-1
                          FORM OF CLASS I-A CERTIFICATE
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE  IS A "REGULAR
INTEREST" IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT," AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE INTERNAL REVENUE CODE OF
1986.
UNLESS THIS  CERTIFICATE  IS PRESENTED BY AN  AUTHORIZED  REPRESENTATIVE  OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER OR ITS AGENT
FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT, AND ANY CERTIFICATE ISSUED
IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY
AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED  REPRESENTATIVE  OF DTC), ANY
TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.
                  WAMU MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
                           SERIES 2001-AR5, CLASS I-A
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of adjustable-rate mortgage loans secured by first liens on one- to- four-family
residential real properties and certain other property held in trust transferred
by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
CUSIP                        $                     Initial Aggregate Class I-A
      --------                --------             Certificate Principal Balance
Certificate No. I-A-         $                     Initial Certificate Principal
                    ---       --------             Balance Of This Certificate
First Distribution Date:                           Scheduled Final Distribution
December 19, 2001                                  Date: [   ]
          THIS CERTIFIES THAT CEDE & CO. is the registered owner of a beneficial
interest  in  the  Trust  Fund  referred  to  below  consisting  of  a  pool  of
adjustable-rate  mortgage  loans secured by first liens on one- to-  four-family
residential  real properties  (the "Mortgage  Loans") and certain other property
held in trust  transferred  to the Trust  Fund by  Credit  Suisse  First  Boston
Mortgage Securities Corp. (the "Depositor"),  and certain related property.  The
Trust Fund was created pursuant to the Pooling and Servicing Agreement, dated as
of December  1, 1999,  as amended  and  restated  as of  November 1, 2001,  (the
"Agreement"),  among the Depositor,  Bank One, National Association,  as trustee
(the  "Trustee",  which term includes any successor  entity under the Agreement)
and Washington Mutual Bank, FA., as seller and servicer, a summary of certain of
the  pertinent  provisions  of which is set forth herein.  This  Certificate  is
issued  under and is subject  to the terms,  provisions  and  conditions  of the
Agreement,  to
                                     A-1-1
which  Agreement  the  Holder of this  Certificate  by virtue of the  acceptance
hereof assents and by which such Holder is bound.
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
2001-AR5  (the "AR5  Certificates"),  which is comprised of the  following  nine
Classes: Class I-A, Class B-1, Class B-2, Class B-3, Class B-4, Class B-5, Class
B-6,  Class Y, and Class I-R.  Pursuant to the  Agreement,  the  Depositor  also
issued the Washington Mutual Bank, FA Mortgage-Backed Pass-Through Certificates,
Series 1999-WM4 (the "WM4 Certificates", and together with the AR5 Certificates,
the "Certificate")  which is comprised of the following ten Classes:  Class A-1,
Class A-2,  Class A-3,  Class A-4,  Class A-5,  Class A-6, Class A-7, Class A-8,
Class A-9 and Class R. Reference is hereby made to the Agreement for a statement
of the  respective  rights  thereunder  of the Depositor and the Trustee and the
Holders  of the  Certificates  and the terms  upon  which the  Certificates  are
authenticated  and  delivered.  This  Certificate  represents an interest in the
Trust Fund, which Trust Fund consists of, among other things,  (i) the Class AR5
Mortgage Loans and all distributions thereon payable after the Class AR5 Cut-off
Date, net of certain amounts in accordance with the provisions of the Agreement,
(ii) REO Property,  (iii) the Certificate  Account and the Custodial Account and
all amounts  deposited  therein  pursuant to the  applicable  provisions  of the
Agreement,  net of any  investment  earnings  thereon,  (iv) the interest of the
Trust Fund in any insurance policies with respect to the Mortgage Loans, (v) the
rights of the  Depositor  assigned to the Trustee  pursuant to Sections 2.01 and
3.01 of the  Agreement,  and (vi) all proceeds of the  conversion,  voluntary or
involuntary, of any of the foregoing into cash or other liquid property.
          This Class I-A Certificate  represents a Percentage  Interest equal to
the Initial  Certificate  Principal  Balance of this Certificate  divided by the
Initial Certificate Principal Balance of the Class I-A Certificates, both as set
forth above.
          The Trustee shall  distribute  from the  Certificate  Account,  to the
extent of available  funds, on the 19th day of each month (each, a "Distribution
Date"), or if such 19th day is not a Business Day, the next succeeding  Business
Day, to the Person in whose name this  Certificate is registered at the close of
business on the last Business Day of the month  immediately  preceding the month
of such distribution  (each, a "Record Date"),  from the Available  Distribution
Amount  for the AR5  Certificates  in an  amount  equal  to the  product  of the
Percentage Interest evidenced by this Certificate and the amount of interest and
principal,  if any required to be distributed to the Class I-A  Certificates  on
such Distribution Date.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          Distributions on this Certificate will be made by the Trustee by check
mailed to the  address  of the Holder  hereof  entitled  thereto at the  address
appearing  in the  Certificate  Register or, if such Holder holds one or more of
this Class of  Certificates  with an  aggregate  initial  Certificate  Principal
Balance of at least $2,500,000 or all of the Certificates of this Class, by wire
transfer in immediately available funds to the account of such Certificateholder
designated  in writing to the Trustee at least five  Business  Days prior to the
applicable  Record Date.  Notwithstanding  the above, the final  distribution on
this  Certificate  will be made after due notice of the  pendency  of such final
distribution and only upon presentation and surrender of this Certificate at the
office or agency designated in such notice.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
                                     A-1-2
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this  Certificate.  The  Agreement  also  permits the  Depositor,  the
Servicer,  the Seller and the Trustee to amend certain terms and  conditions set
forth in the Agreement without the consent of Holders of the Certificates.
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          The Class I-A Certificates  will be issued in fully registered form in
minimum  denominations of $25,000 Certificate  Principal Balance and in integral
multiples of $1,000 in excess of such amount.  As provided in the  Agreement and
subject  to  certain   limitations   therein  set  forth,  this  Certificate  is
exchangeable  for  one or  more  new  Certificates  of  the  same  Class  and of
authorized  denominations  evidencing  a like  aggregate  Certificate  Principal
Balance, as requested by the Holder surrendering the same.
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
          The  obligations  and  responsibilities  of the Servicer,  the Seller,
Depositor  and the Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the Trust Fund of all remaining
Mortgage  Loans and all  property  acquired in respect of such  Mortgage  Loans,
thereby effecting early retirement of the Certificates,  (b) twelve months after
the maturity or other  liquidation (or any advance with respect  thereto) of the
last  Mortgage  Loan  remaining  in the Trust  Fund and the  disposition  of all
property  acquired  upon  foreclosure  or deed in  lieu  of  foreclosure  of any
Mortgage  Loan or (c) the agreement by all  Certificateholders  to terminate the
Trust REMIC,  REMIC I and REMIC II. As provided in the  Agreement,  the right to
purchase all Mortgage  Loans  pursuant to clause (a) above shall be  conditioned
upon the unpaid  Principal  Balances of such Mortgage  Loans, at the
                                     A-1-3
time of any  such  repurchase,  aggregating  less  than or  equal  to 10% of the
aggregate Principal Balances thereof as of the Cut-off Date.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                     A-1-4
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                        BANK ONE, NATIONAL ASSOCIATION
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
      ---------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
    --------------------------------
    Authorized Officer
                                     A-1-5
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                     A-1-6
                                   EXHIBIT A-2
                      FORM OF CLASS B-[1][2][3] CERTIFICATE
THIS  CERTIFICATE IS  SUBORDINATED  IN RIGHT OF PAYMENT TO THE CLASS II A, CLASS
R-I AND  CLASS  R-II  CERTIFICATES  [CLASS  B-1  CERTIFICATES]  [AND  CLASS  B-2
CERTIFICATES] AS DESCRIBED IN THE AGREEMENT (AS DEFINED BELOW).
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE  IS A "REGULAR
INTEREST" IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT," AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE INTERNAL REVENUE CODE OF
1986 (THE "CODE").
UNLESS THIS  CERTIFICATE  IS PRESENTED BY AN  AUTHORIZED  REPRESENTATIVE  OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER OR ITS AGENT
FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT, AND ANY CERTIFICATE ISSUED
IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY
AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED  REPRESENTATIVE  OF DTC), ANY
TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.
ANY TRANSFEREE OF THIS  CERTIFICATE WILL BE DEEMED TO HAVE REPRESENTED BY VIRTUE
OF ITS PURCHASE OR HOLDING OF THIS  CERTIFICATE (OR INTEREST HEREIN) THAT EITHER
(A) SUCH TRANSFEREE IS NOT AN INVESTMENT MANAGER, A NAMED FIDUCIARY OR A TRUSTEE
OF ANY PLAN) ACTING,  DIRECTLY OR  INDIRECTLY,  ON BEHALF OF OR  PURCHASING  ANY
CERTIFICATE  WITH  "PLAN  ASSETS"  OF ANY PLAN (A "PLAN  INVESTOR"),  (B) IT HAS
ACQUIRED AND IS HOLDING SUCH  CERTIFICATE IN RELIANCE ON PROHIBITED  TRANSACTION
EXEMPTION  ("PTE") 89-90,  59 FED. REG. 42597 (OCTOBER 17, 1989),  AS AMENDED BY
PTE 97-34,  62 FED. REG.  39021 (JULY 21, 1997),  AND PTE 2000-58,  65 FED. REG.
67765 (NOVEMBER 13, 2000) (THE "EXEMPTION"),  AND THAT IT UNDERSTANDS THAT THERE
ARE CERTAIN CONDITIONS TO THE AVAILABILITY OF THE EXEMPTION  INCLUDING THAT SUCH
CERTIFICATE  MUST BE RATED,  AT THE TIME OF PURCHASE,  NOT LOWER THAN "BBB-" (OR
ITS EQUIVALENT) BY STANDARD & POOR'S, FITCH OR ▇▇▇▇▇'▇ OR (C) (I) THE TRANSFEREE
IS AN INSURANCE  COMPANY,  (II) THE SOURCE OF FUNDS TO BE USED BY IT TO PURCHASE
THE CERTIFICATE IS AN "INSURANCE COMPANY GENERAL ACCOUNT" (WITHIN THE MEANING OF
DEPARTMENT OF LABOR PROHIBITED  TRANSACTION CLASS EXEMPTION ("PTCE") 95-60), AND
(III) THE  CONDITIONS  SET FORTH IN  SECTIONS  I AND III OF PTCE 95-60 HAVE BEEN
SATISFIED  (EACH ENTITY THAT SATISFIES  THIS CLAUSE (C), A "COMPLYING  INSURANCE
COMPANY).
IF THIS  CERTIFICATE (OR ANY INTEREST  HEREIN) IS ACQUIRED OR HELD BY ANY PERSON
THAT DOES NOT SATISFY THE CONDITIONS DESCRIBED IN THE PRECEDING PARAGRAPH,  THEN
THE LAST  PRECEDING  TRANSFEREE  THAT  EITHER (I) IS NOT A PLAN  INVESTOR,  (II)
ACQUIRED SUCH  CERTIFICATE IN
                                     A-2-1
COMPLIANCE  WITH THE RFC EXEMPTION,  OR (III) IS A COMPLYING  INSURANCE  COMPANY
SHALL BE RESTORED, TO THE EXTENT PERMITTED BY LAW, TO ALL RIGHTS AND OBLIGATIONS
AS  CERTIFICATE  OWNER THEREOF  RETROACTIVE TO THE DATE OF SUCH TRANSFER OF THIS
CERTIFICATE.  THE TRUSTEE  SHALL BE UNDER NO  LIABILITY TO ANY PERSON FOR MAKING
ANY PAYMENTS DUE ON THIS CERTIFICATE TO SUCH PRECEDING TRANSFEREE.
ANY PURPORTED CERTIFICATE OWNER WHOSE ACQUISITION OR HOLDING OF THIS CERTIFICATE
(OR INTEREST  HEREIN) WAS EFFECTED IN VIOLATION OF THE  RESTRICTIONS  IN SECTION
5.02(E) OF THE POOLING AND SERVICING AGREEMENT SHALL INDEMNIFY AND HOLD HARMLESS
THE COMPANY, THE TRUSTEE, THE SERVICER, ANY SUBSERVICER, AND THE TRUST FUND FROM
AND AGAINST ANY AND ALL LIABILITIES,  CLAIMS, COSTS OR EXPENSES INCURRED BY SUCH
PARTIES AS A RESULT OF SUCH ACQUISITION OR HOLDING.
                  WAMU MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
                       SERIES 2001-AR5, CLASS B-[1][2][3]
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of adjustable-rate mortgage loans secured by first liens on one- to- four-family
residential real properties and certain other property held in trust transferred
by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
CUSIP                            $              Initial Aggregate Class B-[1][2]
      ----------                  ---------     [3]Certificate Principal Balance
Certificate No. B-[1][2][3]-     $              Initial Certificate Principal
                            ---   ---------     Balance Of This Certificate
First Distribution Date:                        Scheduled Final Distribution
December 19, 2001                               Date: [   ]
          THIS CERTIFIES THAT CEDE & CO. is the registered owner of a beneficial
interest  in  the  Trust  Fund  referred  to  below  consisting  of  a  pool  of
adjustable-rate  mortgage  loans secured by first liens on one- to-  four-family
residential  real properties  (the "Mortgage  Loans") and certain other property
held in trust  transferred  to the Trust  Fund by  Credit  Suisse  First  Boston
Mortgage Securities Corp. (the "Depositor"),  and certain related property.  The
Trust Fund was created pursuant to the Pooling and Servicing Agreement, dated as
of December  1, 1999,  as amended  and  restated  as of  November 1, 2001,  (the
"Agreement"),  among the Depositor,  Bank One, National Association,  as trustee
(the  "Trustee",  which term includes any successor  entity under the Agreement)
and Washington Mutual Bank, FA., as seller and servicer, a summary of certain of
the  pertinent  provisions  of which is set forth herein.  This  Certificate  is
issued  under and is subject  to the terms,  provisions  and  conditions  of the
Agreement,  to which  Agreement the Holder of this  Certificate by virtue of the
acceptance hereof assents and by which such Holder is bound.
                                     A-2-2
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
2001-AR5  (the "AR5  Certificates"),  which is comprised of the  following  nine
Classes: Class I-A, Class B-1, Class B-2, Class B-3, Class B-4, Class B-5, Class
B-6,  Class Y, and Class I-R.  Pursuant to the  Agreement,  the  Depositor  also
issued the Washington Mutual Bank, FA Mortgage-Backed Pass-Through Certificates,
Series 1999-WM4 (the "WM4 Certificates", and together with the AR5 Certificates,
the "Certificates") which is comprised of the following ten Classes:  Class A-1,
Class A-2,  Class A-3,  Class A-4,  Class A-5,  Class A-6, Class A-7, Class A-8,
Class A-9 and Class R. Reference is hereby made to the Agreement for a statement
of the  respective  rights  thereunder  of the Depositor and the Trustee and the
Holders  of the  Certificates  and the terms  upon  which the  Certificates  are
authenticated  and  delivered.  This  Certificate  represents an interest in the
Trust Fund, which Trust Fund consists of, among other things,  (i) the Class AR5
Mortgage Loans and all distributions thereon payable after the Class AR5 Cut-off
Date, net of certain amounts in accordance with the provisions of the Agreement,
(ii) REO Property,  (iii) the Certificate  Account and the Custodial Account and
all amounts  deposited  therein  pursuant to the  applicable  provisions  of the
Agreement,  net of any  investment  earnings  thereon,  (iv) the interest of the
Trust Fund in any insurance policies with respect to the Mortgage Loans, (v) the
rights of the  Depositor  assigned to the Trustee  pursuant to Sections 2.01 and
3.01 of the  Agreement,  and (vi) all proceeds of the  conversion,  voluntary or
involuntary, of any of the foregoing into cash or other liquid property.
          This Class B-[1][2][3]  Certificate  represents a Percentage  Interest
equal to the Initial  Certificate  Principal Balance of this Certificate divided
by  the  Initial   Certificate   Principal  Balance  of  the  Class  B-[1][2][3]
Certificates, both as set forth above.
          The Trustee shall  distribute  from the  Certificate  Account,  to the
extent of available  funds, on the 19th day of each month (each, a "Distribution
Date"), or if such 19th day is not a Business Day, the next succeeding  Business
Day, to the Person in whose name this  Certificate is registered at the close of
business on the last Business Day of the month  immediately  preceding the month
of such distribution  (each, a "Record Date"),  from the Available  Distribution
Amount  for the AR5  Certificates  in an  amount  equal  to the  product  of the
Percentage Interest evidenced by this Certificate and the amount of interest and
principal,   if  any  required  to  be  distributed  to  the  Class  B-[1][2][3]
Certificates on such Distribution Date.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          Distributions on this Certificate will be made by the Trustee by check
mailed to the  address  of the Holder  hereof  entitled  thereto at the  address
appearing  in the  Certificate  Register or, if such Holder holds one or more of
this Class of  Certificates  with an  aggregate  initial  Certificate  Principal
Balance of at least $2,500,000 or all of the Certificates of this Class, by wire
transfer in immediately available funds to the account of such Certificateholder
designated  in writing to the Trustee at least five  Business  Days prior to the
applicable  Record Date.  Notwithstanding  the above, the final  distribution on
this  Certificate  will be made after due notice of the  pendency  of such final
distribution and only upon presentation and surrender of this Certificate at the
office or agency designated in such notice.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
                                     A-2-3
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this  Certificate.  The  Agreement  also  permits the  Depositor,  the
Servicer,  the Seller and the Trustee to amend certain terms and  conditions set
forth in the Agreement without the consent of Holders of the Certificates.
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          As described above, no transfer of the Class B-[1][2][3]  Certificates
will be made unless (i) the Trustee has received either an opinion of counsel or
a  representation  letter,  each as described in the Agreement,  relating to the
permissibility  of such  transfer  under ERISA and Section 4975 of the Code,  or
(ii) this Certificate is held by a Depository, in which case the Transferee will
be deemed to have made  representations  relating to the  permissibility of such
transfer  under  ERISA and Section  4975 of the Code,  as  described  in Section
6.02(f) of the Agreement.  In addition,  any purported  Certificate  Owner whose
acquisition or holding of this  Certificate (or interest herein) was effected in
violation  of  the  restrictions  in  Section  6.02(f)  of the  Agreement  shall
indemnify  and hold  harmless the  Depositor,  the Trustee,  the  Servicer,  any
Subservicer,  and the  Trust  Fund  from and  against  any and all  liabilities,
claims,  costs  or  expenses  incurred  by  such  parties  as a  result  of such
acquisition or holding.
          The Class B-[1][2][3]  Certificates will be issued in fully registered
form in minimum  denominations of $25,000  Certificate  Principal Balance and in
integral  multiples  of  $1,000 in excess of such  amount.  As  provided  in the
Agreement and subject to certain limitations therein set forth, this Certificate
is  exchangeable  for one or more  new  Certificates  of the same  Class  and of
authorized  denominations  evidencing  a like  aggregate  Certificate  Principal
Balance, as requested by the Holder surrendering the same.
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
                                     A-2-4
          The  obligations  and  responsibilities  of the Servicer,  the Seller,
Depositor  and the Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the Trust Fund of all remaining
Mortgage  Loans and all  property  acquired in respect of such  Mortgage  Loans,
thereby effecting early retirement of the Certificates,  (b) twelve months after
the maturity or other  liquidation (or any advance with respect  thereto) of the
last  Mortgage  Loan  remaining  in the Trust  Fund and the  disposition  of all
property  acquired  upon  foreclosure  or deed in  lieu  of  foreclosure  of any
Mortgage  Loan or (c) the agreement by all  Certificateholders  to terminate the
Trust REMIC,  REMIC I and REMIC II. As provided in the  Agreement,  the right to
purchase all Mortgage  Loans  pursuant to clause (a) above shall be  conditioned
upon the unpaid  Principal  Balances of such Mortgage  Loans, at the time of any
such  repurchase,  aggregating  less  than  or  equal  to 10%  of the  aggregate
Principal Balances thereof as of the Cut-off Date.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                     A-2-5
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                        BANK ONE, NATIONAL ASSOCIATION
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
      ---------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
    -------------------------------
    Authorized Officer
                                     A-2-6
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                     A-2-7
                                   EXHIBIT A-3
                      FORM OF CLASS B-[4][5][6] CERTIFICATE
THIS  CERTIFICATE IS  SUBORDINATED  IN RIGHT OF PAYMENT TO THE CLASS II A, CLASS
R-I  AND  CLASS  R-II   CERTIFICATES   [CLASS  B-1   CERTIFICATES]   [CLASS  B-2
CERTIFICATES]  [CLASS B-3 CERTIFICATES]  [CLASS B-$ CERTIFICATES] [AND CLASS B-5
CERTIFICATES] AS DESCRIBED IN THE AGREEMENT (AS DEFINED BELOW).
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE  IS A "REGULAR
INTEREST" IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT," AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE INTERNAL REVENUE CODE OF
1986 (THE "CODE").
THIS  CERTIFICATE  HAS NOT BEEN AND WILL NOT BE REGISTERED  UNDER THE SECURITIES
ACT OF 1933,  AS  AMENDED,  OR THE  SECURITIES  LAWS OF ANY STATE AND MAY NOT BE
RESOLD OR TRANSFERRED  UNLESS IT IS REGISTERED  PURSUANT TO SUCH ACT AND LAWS OR
IS SOLD OR TRANSFERRED IN TRANSACTIONS  WHICH ARE EXEMPT FROM REGISTRATION UNDER
SUCH ACT AND UNDER  APPLICABLE  STATE LAW AND IS TRANSFERRED IN ACCORDANCE  WITH
THE PROVISIONS OF SECTION 5.02 OF THE AGREEMENT.
UNLESS THIS  CERTIFICATE  IS PRESENTED BY AN  AUTHORIZED  REPRESENTATIVE  OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER OR ITS AGENT
FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT, AND ANY CERTIFICATE ISSUED
IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY
AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED  REPRESENTATIVE  OF DTC), ANY
TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.
ANY TRANSFEREE OF THIS  CERTIFICATE WILL BE DEEMED TO HAVE REPRESENTED BY VIRTUE
OF ITS PURCHASE OR HOLDING OF THIS  CERTIFICATE  (OR  INTEREST  HEREIN) THAT THE
PURCHASE  OF THIS  CERTIFICATE  WILL NOT  CONSTITUTE  OR RESULT IN A  NON-EXEMPT
PROHIBITED  TRANSACTION  UNDER  SECTION 406 OF THE  EMPLOYEE  RETIREMENT  INCOME
SECURITY ACT OF 1974, AS AMENDED ("ERISA"), OR SECTION 4975 OF THE CODE AND WILL
NOT  SUBJECT THE  SERVICER,  THE  COMPANY OR THE  TRUSTEE TO ANY  OBLIGATION  OR
LIABILITY IN ADDITION TO THOSE UNDERTAKEN IN THE AGREEMENT.
IF THIS  CERTIFICATE (OR ANY INTEREST  HEREIN) IS ACQUIRED OR HELD BY ANY PERSON
THAT DOES NOT SATISFY THE CONDITIONS DESCRIBED IN THE PRECEDING PARAGRAPH,  THEN
THE LAST PRECEDING  TRANSFEREE THAT THE OWNERSHIP THEREOF WILL NOT CONSTITUTE OR
RESULT IN A NON-EXEMPT  PROHIBITED  TRANSACTION  UNDER SECTION 406 OF ERISA,  OR
SECTION 4975 OF THE CODE AND WILL NOT SUBJECT THE  SERVICER,  THE COMPANY OR THE
TRUSTEE TO ANY  OBLIGATION  OR LIABILITY IN ADDITION TO THOSE
                                     A-3-1
UNDERTAKEN IN THE AGREEMENT,  TO THE EXTENT  PERMITTED BY LAW, TO ALL RIGHTS AND
OBLIGATIONS  AS  CERTIFICATE  OWNER  THEREOF  RETROACTIVE  TO THE  DATE  OF SUCH
TRANSFER OF THIS  CERTIFICATE.  THE TRUSTEE  SHALL BE UNDER NO  LIABILITY TO ANY
PERSON  FOR  MAKING  ANY  PAYMENTS  DUE ON THIS  CERTIFICATE  TO SUCH  PRECEDING
TRANSFEREE.
                                     A-3-2
                  WAMU MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
                       SERIES 2001-AR5, CLASS B-[4][5][6]
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of adjustable-rate mortgage loans secured by first liens on one- to- four-family
residential real properties and certain other property held in trust transferred
by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
CUSIP                            $              Initial Aggregate Class B-[4][5]
      ----------                  ----------    [6]Certificate Principal Balance
Certificate No. B-[4][5][6]-     $              Initial Certificate Principal
                            ---   ----------    Balance Of This Certificate
First Distribution Date:                        Scheduled Final Distribution
December 19, 2001                               Date: [   ]
          THIS CERTIFIES THAT CEDE & CO. is the registered owner of a beneficial
interest  in  the  Trust  Fund  referred  to  below  consisting  of  a  pool  of
adjustable-rate  mortgage  loans secured by first liens on one- to-  four-family
residential  real properties  (the "Mortgage  Loans") and certain other property
held in trust  transferred  to the Trust  Fund by  Credit  Suisse  First  Boston
Mortgage Securities Corp. (the "Depositor"),  and certain related property.  The
Trust Fund was created pursuant to the Pooling and Servicing Agreement, dated as
of December  1, 1999,  as amended  and  restated  as of  November 1, 2001,  (the
"Agreement"),  among the Depositor,  Bank One, National Association,  as trustee
(the  "Trustee",  which term includes any successor  entity under the Agreement)
and Washington Mutual Bank, FA., as seller and servicer, a summary of certain of
the  pertinent  provisions  of which is set forth herein.  This  Certificate  is
issued  under and is subject  to the terms,  provisions  and  conditions  of the
Agreement,  to which  Agreement the Holder of this  Certificate by virtue of the
acceptance hereof assents and by which such Holder is bound.
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
2001-AR5  (the "AR5  Certificates"),  which is comprised of the  following  nine
Classes: Class I-A, Class B-1, Class B-2, Class B-3, Class B-4, Class B-5, Class
B-6, Class Y and Class I-R. Pursuant to the Agreement, the Depositor also issued
the Washington Mutual Bank, FA Mortgage-Backed Pass-Through Certificates, Series
1999-WM4 (the "WM4  Certificates",  and together with the AR5 Certificates,  the
"Certificates")  which is comprised  of the  following  ten Classes:  Class A-1,
Class A-2,  Class A-3,  Class A-4,  Class A-5,  Class A-6, Class A-7, Class A-8,
Class A-9 and Class R. Reference is hereby made to the Agreement for a statement
of the  respective  rights  thereunder  of the Depositor and the Trustee and the
Holders  of the  Certificates  and the terms  upon  which the  Certificates  are
authenticated  and  delivered.  This  Certificate  represents an interest in the
Trust Fund, which Trust Fund consists of, among other things,  (i) the Class AR5
Mortgage Loans and all distributions thereon payable after the Class AR5 Cut-off
Date, net of certain amounts in accordance with the provisions of the Agreement,
(ii) REO Property,  (iii) the Certificate  Account and the Custodial Account and
all amounts  deposited  therein  pursuant to the  applicable  provisions  of the
Agreement,  net of any  investment  earnings  thereon,  (iv) the interest of the
Trust Fund in any insurance policies with respect to
                                     A-3-3
the  Mortgage  Loans,  (v) the rights of the  Depositor  assigned to the Trustee
pursuant to Sections  2.01 and 3.01 of the  Agreement,  and (vi) all proceeds of
the conversion,  voluntary or involuntary,  of any of the foregoing into cash or
other liquid property.
          This Class B-[4][5][6]  Certificate  represents a Percentage  Interest
equal to the Initial  Certificate  Principal Balance of this Certificate divided
by  the  Initial   Certificate   Principal  Balance  of  the  Class  B-[4][5][6]
Certificates, both as set forth above.
          The Trustee shall  distribute  from the  Certificate  Account,  to the
extent of available  funds, on the 19th day of each month (each, a "Distribution
Date"), or if such 19th day is not a Business Day, the next succeeding  Business
Day, to the Person in whose name this  Certificate is registered at the close of
business on the last Business Day of the month  immediately  preceding the month
of such distribution  (each, a "Record Date"),  from the Available  Distribution
Amount  for the AR5  Certificates  in an  amount  equal  to the  product  of the
Percentage Interest evidenced by this Certificate and the amount of interest and
principal,   if  any  required  to  be  distributed  to  the  Class  B-[4][5][6]
Certificates on such Distribution Date.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          Distributions on this Certificate will be made by the Trustee by check
mailed to the  address  of the Holder  hereof  entitled  thereto at the  address
appearing  in the  Certificate  Register or, if such Holder holds one or more of
this Class of  Certificates  with an  aggregate  initial  Certificate  Principal
Balance of at least $2,500,000 or all of the Certificates of this Class, by wire
transfer in immediately available funds to the account of such Certificateholder
designated  in writing to the Trustee at least five  Business  Days prior to the
applicable  Record Date.  Notwithstanding  the above, the final  distribution on
this  Certificate  will be made after due notice of the  pendency  of such final
distribution and only upon presentation and surrender of this Certificate at the
office or agency designated in such notice.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this  Certificate.  The  Agreement  also  permits the  Depositor,  the
Servicer,
                                     A-3-4
the Seller and the Trustee to amend  certain terms and  conditions  set forth in
the Agreement without the consent of Holders of the Certificates.
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          No transfer of this Class B-[4][5][6]  Certificate will be made unless
such transfer is exempt from the registration requirements of the Securities Act
of 1933, as amended,  and any  applicable  state  securities  laws or is made in
accordance  with said Act and laws.  In the event that such a transfer  is to be
made,  (i) the  Trustee  or the  Company  may  require  an  opinion  of  counsel
acceptable  to and in form and  substance  satisfactory  to the  Trustee and the
Depositor that such transfer is exempt (describing the applicable  exemption and
the  basis  therefor)  from  or is  being  made  pursuant  to  the  registration
requirements  of the Securities  Act of 1933, as amended,  and of any applicable
statute of any state and (ii) the transferee shall execute an investment  letter
in the form  described by the  Agreement.  The Holder hereof  desiring to effect
such  transfer  shall,  and does hereby agree to,  indemnify  the  Trustee,  the
Depositor,  the Servicer and the Certificate  Registrar  acting on behalf of the
Trustee  against any liability  that may result if the transfer is not so exempt
or is not made in  accordance  with such Federal and state laws.  In  connection
with any such  transfer,  the Trustee will also require either (i) an opinion of
counsel acceptable to and in form and substance satisfactory to the Trustee, the
Depositor and the Servicer with respect to the  permissibility  of such transfer
under the Employee Retirement Income Security Act of 1974, as amended ("ERISA"),
and Section  4975 of the Internal  Revenue Code (the "Code") and stating,  among
other things,  that the  transferee's  acquisition of a Class B Certificate will
not constitute or result in a non-exempt  prohibited  transaction  under Section
406 of ERISA or Section 4975 of the Code or (ii) a representation letter, in the
form as described by the Agreement, either stating that the transferee is not an
employee benefit or other plan subject to the prohibited  transaction provisions
of ERISA or Section 4975 of the Code (a "Plan"),  or any other person (including
an  investment  manager,  a named  fiduciary  or a trustee of any Plan)  acting,
directly or indirectly,  on behalf of or purchasing any  Certificate  with "plan
assets" of any Plan, or stating that the transferee is an insurance company, the
source of funds to be used by it to purchase the  Certificate  is an  "insurance
company general  account"  (within the meaning of Department of Labor Prohibited
Transaction Class Exemption.
          The Class B-[4][5][6]  Certificates will be issued in fully registered
form in minimum  denominations of $25,000  Certificate  Principal Balance and in
integral  multiples  of  $1,000 in excess of such  amount.  As  provided  in the
Agreement and subject to certain limitations therein set forth, this Certificate
is  exchangeable  for one or more  new  Certificates  of the same  Class  and of
authorized  denominations  evidencing  a like  aggregate  Certificate  Principal
Balance, as requested by the Holder surrendering the same.
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
          The  obligations  and  responsibilities  of the Servicer,  the Seller,
Depositor  and the Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the
                                     A-3-5
Trust Fund of all remaining  Mortgage Loans and all property acquired in respect
of such Mortgage Loans,  thereby effecting early retirement of the Certificates,
(b) twelve months after the maturity or other  liquidation  (or any advance with
respect  thereto) of the last Mortgage Loan  remaining in the Trust Fund and the
disposition  of all  property  acquired  upon  foreclosure  or  deed  in lieu of
foreclosure of any Mortgage Loan or (c) the agreement by all  Certificateholders
to  terminate  the  Trust  REMIC,  REMIC I and  REMIC  II.  As  provided  in the
Agreement, the right to purchase all Mortgage Loans pursuant to clause (a) above
shall be conditioned upon the unpaid Principal  Balances of such Mortgage Loans,
at the time of any such repurchase, aggregating less than or equal to 10% of the
aggregate Principal Balances thereof as of the Cut-off Date.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                     A-3-6
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                       BANK ONE, NATIONAL ASSOCIATION
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
      ---------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
    --------------------------------
    Authorized Officer
                                     A-3-7
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                     A-3-8
                                    EXHIBIT B
                           FORM OF CLASS R CERTIFICATE
THIS  CERTIFICATE  HAS NOT BEEN AND WILL NOT BE REGISTERED  UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR THE SECURITIES LAWS OF ANY STATE AND MAY
NOT BE RESOLD OR  TRANSFERRED  UNLESS IT IS REGISTERED  PURSUANT TO SUCH ACT AND
LAWS OR IS SOLD OR TRANSFERRED IN TRANSACTIONS THAT ARE EXEMPT FROM REGISTRATION
UNDER SUCH ACT AND UNDER  APPLICABLE  STATE LAW AND IS TRANSFERRED IN ACCORDANCE
WITH THE PROVISIONS OF SECTION 6.02 OF THE AGREEMENT REFERRED TO HEREIN.
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE IS A "RESIDUAL
INTEREST"  IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT" AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE INTERNAL REVENUE CODE OF
1986 (THE  "CODE").  THIS  CERTIFICATE  MAY NOT BE  TRANSFERRED  TO A NON-UNITED
STATES PERSON.
THIS  CERTIFICATE  DOES NOT  REPRESENT  AN INTEREST IN OR  OBLIGATION  OF CREDIT
SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP., WASHINGTON MUTUAL BANK, FA OR THE
TRUSTEE  REFERRED TO BELOW, OR OF ANY OF THEIR  AFFILIATES.  THIS CERTIFICATE IS
NOT GUARANTEED OR INSURED BY ANY GOVERNMENT AGENCY OR INSTRUMENTALITY.
ANY SALE,  TRANSFER OR OTHER DISPOSITION OF THIS CLASS R CERTIFICATE MAY BE MADE
ONLY IF THE PROPOSED  TRANSFEREE PROVIDES A TRANSFER AFFIDAVIT TO THE TRUSTEE TO
THE  EFFECT  THAT (1) SUCH  TRANSFEREE  AGREES  TO BE BOUND BY THE  TERMS OF THE
AGREEMENT AND ALL RESTRICTIONS SET FORTH ON THE FACE HEREOF, (2) SUCH TRANSFEREE
IS NOT EITHER (A) THE UNITED STATES, ANY STATE OR POLITICAL SUBDIVISION THEREOF,
ANY  FOREIGN  GOVERNMENT,  ANY  INTERNATIONAL  ORGANIZATION,  OR ANY  AGENCY  OR
INSTRUMENTALITY  OF ANY OF THE  FOREGOING,  (B) ANY  ORGANIZATION  (OTHER THAN A
COOPERATIVE DESCRIBED IN SECTION 521 OF THE CODE) WHICH IS EXEMPT FROM THE TAXES
IMPOSED BY CHAPTER 1 OF THE CODE UNLESS SUCH  ORGANIZATION IS SUBJECT TO THE TAX
IMPOSED BY SECTION 511 OF THE CODE,  (C) AN  ELECTING  LARGE  PARTNERSHIP  UNDER
SECTION 775 OF THE CODE OR ANY ORGANIZATION  DESCRIBED IN SECTION  1381(a)(2)(C)
OF THE CODE, (ANY SUCH PERSON DESCRIBED IN THE FOREGOING CLAUSES (A), (B) OR (C)
BEING HEREINAFTER REFERRED TO AS A "DISQUALIFIED  ORGANIZATION") OR (D) AN AGENT
OF A DISQUALIFIED ORGANIZATION, AND (3) NO PURPOSE OF SUCH TRANSFER IS TO ENABLE
THE  TRANSFEROR TO IMPEDE THE  ASSESSMENT  OR COLLECTION OF TAX. SUCH  AFFIDAVIT
SHALL  INCLUDE  CERTAIN  REPRESENTATIONS  AS TO THE  FINANCIAL  CONDITION OF THE
PROPOSED  TRANSFEREE.   NOTWITHSTANDING  THE  REGISTRATION  IN  THE  CERTIFICATE
REGISTER OF ANY TRANSFER,  SALE OR OTHER DISPOSITION OF THIS CLASS R CERTIFICATE
TO A DISQUALIFIED ORGANIZATION OR AN AGENT OF A DISQUALIFIED ORGANIZATION,  SUCH
REGISTRATION  SHALL BE DEEMED TO BE OF NO LEGAL FORCE OR EFFECT  WHATSOEVER  AND
SUCH  PERSON  SHALL  NOT BE  DEEMED
                                      B-1
TO BE A CERTIFICATEHOLDER FOR ANY PURPOSE HEREUNDER,  INCLUDING, BUT NOT LIMITED
TO, THE RECEIPT OF DISTRIBUTIONS ON THIS CERTIFICATE. EACH HOLDER OF THE CLASS R
CERTIFICATE BY ACCEPTANCE OF THIS CERTIFICATE  SHALL BE DEEMED TO HAVE CONSENTED
TO THE PROVISIONS OF THIS PARAGRAPH.
NO TRANSFER OF THIS CERTIFICATE MAY BE MADE TO AN EMPLOYEE BENEFIT OR OTHER PLAN
SUBJECT TO THE  EMPLOYEE  RETIREMENT  INCOME  SECURITY  ACT OF 1974,  AS AMENDED
("ERISA"), OR SECTION 4975 OF THE CODE.
                           WASHINGTON MUTUAL BANK, FA
                    MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
                            SERIES 1999-WM4, CLASS R
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of fixed-rate and adjustable-rate, mortgage loans secured by first liens on one-
to- four-family,  residential real properties and certain other property held in
trust transferred by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
Certificate No. R               100%          Percentage Interest Represented By
                                              This Certificate
First Distribution Date:                      Scheduled Final Distribution
January 19, 2000                              Date: [   ]
          THIS CERTIFIES THAT is the registered  owner of a beneficial  interest
in the Trust Fund  referred  to below  consisting  of a pool of  fixed-rate  and
adjustable-rate  mortgage  loans secured by first liens on one- to-  four-family
residential  real properties  (the "Mortgage  Loans") and certain other property
held in trust  transferred  to the Trust  Fund by  Credit  Suisse  First  Boston
Mortgage Securities Corp. (the "Depositor"),  and certain related property.  The
Trust Fund was created pursuant to the Pooling and Servicing Agreement, dated as
of November 1, 1999 (the "Agreement"),  among the Depositor,  Bank One, National
Association, as trustee (the "Trustee", which term includes any successor entity
under the Agreement) and Washington Mutual Bank, FA., as seller and servicer,  a
summary of certain of the  pertinent  provisions  of which is set forth  herein.
This  Certificate  is issued under and is subject to the terms,  provisions  and
conditions of the Agreement,  to which Agreement the Holder of this  Certificate
by virtue of the acceptance hereof assents and by which such Holder is bound.
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
1999-WM4 (the "Certificates"),  which is comprised of the following ten Classes:
Class A-1,  Class A-2,  Class A-3,  Class A-4, Class A -5, Class A-6, Class A-7,
Class A-8,  Class A-9 and Class R. Reference is hereby made to the Agreement for
a statement of the respective rights thereunder of the Depositor and the Trustee
and the Holders of the  Certificates  and the terms upon which the  Certificates
are authenticated and delivered.  This Certificate represents an interest in the
Trust
                                      B-2
Fund,  which Trust Fund consists of, among other things,  (i) the Mortgage Loans
and all  distributions  thereon  payable after the Cut-off Date,  net of certain
amounts in accordance  with the provisions of the Agreement,  (ii) REO Property,
(iii)  the  Certificate  Account  and the  Custodial  Account  and  all  amounts
deposited therein pursuant to the applicable provisions of the Agreement, net of
any  investment  earnings  thereon,  (iv) the  interest of the Trust Fund in any
insurance  policies  with respect to the Mortgage  Loans,  (v) the rights of the
Depositor  assigned  to the Trustee  pursuant  to Sections  2.01 and 3.01 of the
Agreement, and (vi) all proceeds of the conversion, voluntary or involuntary, of
any of the foregoing into cash or other liquid property.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this  Certificate.  The  Agreement  also  permits the  Depositor,  the
Servicer,  the Seller and the Trustee to amend certain terms and  conditions set
forth in the Agreement  without the consent of Holders of the  Certificates.  At
any time  that any of the  Class of  Certificates  are  outstanding,  99% of all
Voting Rights will be allocated to the Holders of the  Certificates  (other than
the Class R Certificates),  in proportion to their then outstanding  Certificate
Principal  Balances  and 1.00% of all Voting  Rights  will be  allocated  to the
Holders of the Class R Certificates.
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          The Class R Certificates  will be issued in fully  registered  form in
minimum Percentage  Interests of 20% and integral multiples thereof. As provided
in the  Agreement  and subject to certain  limitations  therein set forth,  this
Certificate is exchangeable  for one or more new  Certificates of the same
                                      B-3
Class  and of  authorized  Percentage  Interests  evidencing  a  like  aggregate
Percentage Interest, as requested by the Holder surrendering the same.
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
          Pursuant  to the  Agreement,  the  Depositor  will make an election to
treat the Trust REMIC, as a real estate mortgage  investment conduit (a "REMIC")
for federal income tax purposes.  The Class R Certificates will be the "residual
interest"  in the  Trust  REMIC  and  all  other  Classes  A  Certificates  will
constitute the "regular interests" in the Trust REMIC.
          The obligations and responsibilities of the Depositor, the Seller, the
Servicer  and the  Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the Trust Fund of all remaining
Mortgage  Loans and all  property  acquired in respect of such  Mortgage  Loans,
thereby effecting early retirement of the Certificates,  (b) twelve months after
the maturity or other  liquidation (or any advance with respect  thereto) of the
last  Mortgage  Loan  remaining  in the Trust  Fund and the  disposition  of all
property  acquired  upon  foreclosure  or deed in  lieu  of  foreclosure  of any
Mortgage  Loan or (c) the agreement by all  Certificateholders  to terminate the
Trust REMIC.  As provided in the  Agreement,  the right to purchase all Mortgage
Loans  pursuant  to  clause  (a)  above  shall be  conditioned  upon the  unpaid
Principal  Balances of such Mortgage Loans, at the time of any such  repurchase,
aggregating  less  than or  equal  to 10% of the  aggregate  Principal  Balances
thereof as of the Cut-off Date.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                      B-4
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                        BANK ONE, NATIONAL ASSOCIATION,
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
     ----------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
   ----------------------------------
   Authorized Officer
                                      B-5
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                      B-6
                                   EXHIBIT B-1
                          FORM OF CLASS I-R CERTIFICATE
THIS  CERTIFICATE  HAS NOT BEEN AND WILL NOT BE REGISTERED  UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR THE SECURITIES LAWS OF ANY STATE AND MAY
NOT BE RESOLD OR  TRANSFERRED  UNLESS IT IS REGISTERED  PURSUANT TO SUCH ACT AND
LAWS OR IS SOLD OR TRANSFERRED IN TRANSACTIONS THAT ARE EXEMPT FROM REGISTRATION
UNDER SUCH ACT AND UNDER  APPLICABLE  STATE LAW AND IS TRANSFERRED IN ACCORDANCE
WITH THE PROVISIONS OF SECTION 6.02 OF THE AGREEMENT REFERRED TO HEREIN.
SOLELY FOR U.S.  FEDERAL  INCOME TAX PURPOSES,  THIS  CERTIFICATE IS A "RESIDUAL
INTEREST"  IN A "REAL  ESTATE  MORTGAGE  INVESTMENT  CONDUIT" AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G AND 860D OF THE INTERNAL REVENUE CODE OF
1986 (THE  "CODE").  THIS  CERTIFICATE  MAY NOT BE  TRANSFERRED  TO A NON-UNITED
STATES PERSON.
THIS  CERTIFICATE  DOES NOT  REPRESENT  AN INTEREST IN OR  OBLIGATION  OF CREDIT
SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP., WASHINGTON MUTUAL BANK, FA OR THE
TRUSTEE  REFERRED TO BELOW, OR OF ANY OF THEIR  AFFILIATES.  THIS CERTIFICATE IS
NOT GUARANTEED OR INSURED BY ANY GOVERNMENT AGENCY OR INSTRUMENTALITY.
ANY SALE,  TRANSFER OR OTHER  DISPOSITION OF THIS CLASS I-R  CERTIFICATE  MAY BE
MADE ONLY IF THE  PROPOSED  TRANSFEREE  PROVIDES  A  TRANSFER  AFFIDAVIT  TO THE
TRUSTEE TO THE EFFECT THAT (1) SUCH  TRANSFEREE  AGREES TO BE BOUND BY THE TERMS
OF THE AGREEMENT  AND ALL  RESTRICTIONS  SET FORTH ON THE FACE HEREOF,  (2) SUCH
TRANSFEREE  IS NOT  EITHER  (A)  THE  UNITED  STATES,  ANY  STATE  OR  POLITICAL
SUBDIVISION THEREOF, ANY FOREIGN GOVERNMENT, ANY INTERNATIONAL ORGANIZATION,  OR
ANY AGENCY OR  INSTRUMENTALITY  OF ANY OF THE  FOREGOING,  (B) ANY  ORGANIZATION
(OTHER THAN A COOPERATIVE  DESCRIBED IN SECTION 521 OF THE CODE) WHICH IS EXEMPT
FROM THE TAXES  IMPOSED BY CHAPTER 1 OF THE CODE  UNLESS  SUCH  ORGANIZATION  IS
SUBJECT TO THE TAX  IMPOSED BY SECTION 511 OF THE CODE,  (C) AN  ELECTING  LARGE
PARTNERSHIP  UNDER  SECTION  775 OF THE CODE OR ANY  ORGANIZATION  DESCRIBED  IN
SECTION  1381(a)(2)(C)  OF THE CODE, (ANY SUCH PERSON DESCRIBED IN THE FOREGOING
CLAUSES  (A),  (B) OR  (C)  BEING  HEREINAFTER  REFERRED  TO AS A  "DISQUALIFIED
ORGANIZATION")  OR (D) AN  AGENT  OF A  DISQUALIFIED  ORGANIZATION,  AND  (3) NO
PURPOSE OF SUCH TRANSFER IS TO ENABLE THE TRANSFEROR TO IMPEDE THE ASSESSMENT OR
COLLECTION OF TAX. SUCH AFFIDAVIT  SHALL INCLUDE CERTAIN  REPRESENTATIONS  AS TO
THE  FINANCIAL  CONDITION  OF  THE  PROPOSED  TRANSFEREE.   NOTWITHSTANDING  THE
REGISTRATION  IN  THE  CERTIFICATE  REGISTER  OF ANY  TRANSFER,  SALE  OR  OTHER
DISPOSITION OF THIS CLASS I-R  CERTIFICATE TO A DISQUALIFIED  ORGANIZATION OR AN
AGENT OF A DISQUALIFIED ORGANIZATION, SUCH REGISTRATION SHALL BE DEEMED
                                     B-1-1
TO BE OF NO LEGAL FORCE OR EFFECT WHATSOEVER AND SUCH PERSON SHALL NOT BE DEEMED
TO BE A CERTIFICATEHOLDER FOR ANY PURPOSE HEREUNDER,  INCLUDING, BUT NOT LIMITED
TO, THE RECEIPT OF DISTRIBUTIONS ON THIS  CERTIFICATE.  EACH HOLDER OF THE CLASS
I-R  CERTIFICATE  BY  ACCEPTANCE  OF THIS  CERTIFICATE  SHALL BE  DEEMED TO HAVE
CONSENTED TO THE PROVISIONS OF THIS PARAGRAPH.
NO TRANSFER OF THIS CERTIFICATE MAY BE MADE TO AN EMPLOYEE BENEFIT OR OTHER PLAN
SUBJECT TO THE  EMPLOYEE  RETIREMENT  INCOME  SECURITY  ACT OF 1974,  AS AMENDED
("ERISA"), OR SECTION 4975 OF THE CODE.
                  WAMU MORTGAGE-BACKED PASS-THROUGH CERTIFICATE
                        SERIES 2001-AR5, CLASS I-R-[1][2]
Evidencing an undivided  interest in a Trust Fund whose assets consist of a pool
of fixed-rate and adjustable-rate, mortgage loans secured by first liens on one-
to- four-family,  residential real properties and certain other property held in
trust transferred by
              CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
Certificate No. I R-[1][2]      100%          Percentage Interest Represented By
                                              This Certificate
First Distribution Date:                      Scheduled Final Distribution
December 19, 2001                             Date: [   ]
          THIS  CERTIFIES  THAT                  is the  registered  owner  of a
                                 --------------
beneficial  interest in the Trust Fund referred to below consisting of a pool of
adjustable-rate  mortgage  loans secured by first liens on one- to-  four-family
residential  real properties  (the "Mortgage  Loans") and certain other property
held in trust  transferred  to the Trust  Fund by  Credit  Suisse  First  Boston
Mortgage Securities Corp. (the "Depositor"),  and certain related property.  The
Trust Fund was created pursuant to the Pooling and Servicing Agreement, dated as
of December  1, 1999,  as amended  and  restated  as of  November 1, 2001,  (the
"Agreement"),  among the Depositor,  Bank One, National Association,  as trustee
(the  "Trustee",  which term includes any successor  entity under the Agreement)
and Washington Mutual Bank, FA., as seller and servicer, a summary of certain of
the  pertinent  provisions  of which is set forth herein.  This  Certificate  is
issued  under and is subject  to the terms,  provisions  and  conditions  of the
Agreement,  to which  Agreement the Holder of this  Certificate by virtue of the
acceptance hereof assents and by which such Holder is bound.
          This  Certificate is one of a duly authorized issue of certificates by
Credit  Suisse  First  Boston  Mortgage  Securities  Corp.   designated  as  the
Washington Mutual Bank, FA  Mortgage-Backed  Pass-Through  Certificates,  Series
2001-AR5  (the "AR5  Certificates"),  which is comprised of the  following  nine
Classes: Class I-A, Class B-1, Class B-2, Class B-3, Class B-4, Class B-5, Class
B-6, Class Y and Class I-R. This Class I R Certificate  represents the interests
of the Class R-1  Certificate  and the Class R-2  Certificate.  Pursuant  to the
Agreement,   the  Depositor   also  issued  the   Washington   Mutual  Bank,  FA
Mortgage-Backed   Pass-Through   Certificates,   Series   1999-WM4   (the   "WM4
Certificates", and together with the AR5 Certificates, the "Certificates") which
is comprised of the  following  ten Classes:  Class A-1,  Class A-2,  Class A-3,
Class A-4,  Class A-5,  Class A-6,  Class A-7, Class A-8, Class A-9 and
                                     B-1-2
Class R.  Reference  is hereby  made to the  Agreement  for a  statement  of the
respective rights thereunder of the Depositor and the Trustee and the Holders of
the Certificates and the terms upon which the Certificates are authenticated and
delivered.  This  Certificate  represents  an interest in the Trust Fund,  which
Trust Fund consists of, among other things, (i) the Class AR5 Mortgage Loans and
all  distributions  thereon  payable  after the Class AR5 Cut-off  Date,  net of
certain  amounts in accordance  with the provisions of the  Agreement,  (ii) REO
Property,  (iii) the  Certificate  Account  and the  Custodial  Account  and all
amounts  deposited  therein  pursuant  to  the  applicable   provisions  of  the
Agreement,  net of any  investment  earnings  thereon,  (iv) the interest of the
Trust Fund in any insurance policies with respect to the Mortgage Loans, (v) the
rights of the  Depositor  assigned to the Trustee  pursuant to Sections 2.01 and
3.01 of the  Agreement,  and (vi) all proceeds of the  conversion,  voluntary or
involuntary, of any of the foregoing into cash or other liquid property.
          Not later than each  Distribution  Date, the Trustee will send to each
Certificateholder a statement  containing  information  relating to the Mortgage
Loans and payments made to Certificateholders.
          The Agreement  permits,  with certain  exceptions as therein provided,
the amendment  thereof and the modification of the rights and obligations of the
Depositor,  the  Trustee,  the  Servicer  and the  Seller  and the rights of the
Certificateholders  under  the  Agreement  at any  time  by the  Depositor,  the
Servicer,  the  Seller  and the  Trustee  with the  consent  of the  Holders  of
Certificates  evidencing Voting Rights  aggregating not less than 66-2/3% of the
Voting Rights of all the Certificates; PROVIDED, HOWEVER, that no such amendment
may (i) reduce in any  manner  the amount of,  delay the timing of or change the
manner  in  which  payments  received  on  Mortgage  Loans  are  required  to be
distributed in respect of any  Certificate  without the consent of the Holder of
such Certificate, (ii) adversely affect in any material respect the interests of
the  Holders  of a Class of  Certificates  in a manner  other  than in (i) above
without  the  consent of the Holders of  Certificates  evidencing  not less than
66-2/3%  of the  Voting  Rights  of  such  Class,  (iii)  reduce  the  aforesaid
percentages  of Voting  Rights,  the holders of which are required to consent to
any such  amendment,  without the consent of 100% of the Holders of Certificates
of the Class  affected  thereby,  (iv) change the  percentage  of the  Principal
Balance of the Mortgage  Loans  specified in Section  10.01(a) of the  Agreement
relating to optional  termination  of the Trust Fund without the consent of 100%
of the Holders of  Certificates,  (v) modify the  provisions of Section 11.01 of
the  Agreement  without the consent of 100% of the Holders of  Certificates,  or
(vi) terminate the Agreement or the Trust Fund created  hereunder  other than as
provided  in  Article X of the  Agreement  without  the  consent  of 100% of the
Holders of  Certificates.  Any such  consent  by the Holder of this  Certificate
shall be  conclusive  and binding on such Holder and upon all future  Holders of
this  Certificate and of any  Certificate  issued upon the transfer hereof or in
exchange  herefor or in lieu hereof  whether or not  notation of such consent is
made upon this Certificate.
          As  provided  in the  Agreement  and  subject to  certain  limitations
therein  set forth,  the  transfer of this  Certificate  is  registrable  on the
Certificate  Register upon surrender of this  Certificate  for  registration  of
transfer  at the  office or  agency of the  Trustee  designated  therefor,  duly
endorsed  by, or  accompanied  by a written  instrument  of  transfer  in a form
satisfactory  to the Trustee duly executed by the Holder hereof or such ▇▇▇▇▇▇'s
attorney duly authorized in writing,  and thereupon one or more new Certificates
of the same Class and of authorized  denominations,  and for the same  aggregate
interest  in the  Trust  Fund will be issued  to the  designated  transferee  or
transferees.
          The Class I-R Certificates  will be issued in fully registered form in
minimum Percentage  Interests of 20% and integral multiples thereof. As provided
in the  Agreement  and subject to certain  limitations  therein set forth,  this
Certificate is exchangeable  for one or more new  Certificates of the same Class
and of authorized  Percentage  Interests  evidencing a like aggregate Percentage
Interest, as requested by the Holder surrendering the same.
                                     B-1-3
          No service charge will be made for such  registrations of transfers or
exchanges,  but the Trustee may require payment of a sum sufficient to cover any
tax or other governmental  charge payable in connection  therewith.  The Trustee
and any agent of the Trustee may treat the person in whose name this Certificate
is registered as the owner hereof for all purposes,  and neither the Trustee nor
any such agent thereof shall be affected by notice to the contrary.
          The Class R-1  Certificate  evidenced  by this Class I-R  Certificates
will  be the  "residual  interest"  in  REMIC I and the  Class  R-2  Certificate
evidenced  by this Class I-R  Certificates  will be the  "residual  interest" in
REMIC II and.
          The obligations and responsibilities of the Depositor, the Seller, the
Servicer  and the  Trustee  created by the  Agreement  will  terminate  upon the
earlier of (a) the purchase by the Servicer from the Trust Fund of all remaining
Mortgage  Loans and all  property  acquired in respect of such  Mortgage  Loans,
thereby effecting early retirement of the Certificates,  (b) twelve months after
the maturity or other  liquidation (or any advance with respect  thereto) of the
last  Mortgage  Loan  remaining  in the Trust  Fund and the  disposition  of all
property  acquired  upon  foreclosure  or deed in  lieu  of  foreclosure  of any
Mortgage Loan or (c) the agreement by all  Certificateholders to terminate REMIC
I and REMIC II.
          Any term used herein that is defined in the  Agreement  shall have the
meaning  assigned  in  the  Agreement,   and  nothing  herein  shall  be  deemed
inconsistent  with that meaning.  If the terms hereof are inconsistent  with the
Agreement, the Agreement shall control.
          Unless the certificate of  authentication  hereon has been executed by
or on behalf of the Trustee by manual  signature,  this Certificate shall not be
entitled to any benefit under the  Agreement or be valid or  obligatory  for any
purpose.
          The  recitals  contained  herein shall be taken as  statements  of the
Depositor and not of the Trustee.  The Trustee assumes no responsibility for the
correctness  of the  statements  contained  in this  Certificate  and  makes  no
representation  as to  the  validity  or  sufficiency  of  the  Agreement,  this
Certificate, any Mortgage Loan or any related document.
                                     B-1-4
          IN WITNESS WHEREOF, the Trustee has caused this Certificate to be duly
executed under its corporate seal.
                                        BANK ONE, NATIONAL ASSOCIATION,
                                          solely as Trustee and not individually
                                        By:
                                            ------------------------------------
                                            Authorized Officer
                          CERTIFICATE OF AUTHENTICATION
This is one of the Certificates referred to in the within-mentioned Agreement.
Date:
      ---------------------
BANK ONE, NATIONAL ASSOCIATION,
as Trustee
By:
    --------------------------------
    Authorized Officer
                                     B-1-5
                                   ASSIGNMENT
          FOR VALUE  RECEIVED the  undersigned  ▇▇▇▇▇▇  ▇▇▇▇(s),  assign(s)  and
transfer(s) unto
                 ---------------------------------------------------------------
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(Please  print or typewrite  name and  address,  including  postal zip code,  or
assignee)  the  undivided  interest  in the Trust Fund  evidenced  by the within
Certificate  and  hereby  authorize(s)  the  transfer  of  registration  of such
interest to the assignee on the Certificate Register.
          I (we) further  direct the Trustee to issue a new  Certificate  of the
same Class and of a like Initial  Certificate  Principal  Balance and  undivided
interest  in the Trust Fund to the  above-named  assignee  and to  deliver  such
Certificate to the following address:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Dated:
       -----------------
------------------------------        ------------------------------------------
Social Security or other Tax          Signature  by or on  behalf of  assignor
Identification No. of Assignee        (signature must be signed as registered)
                                      ------------------------------------------
                                      Signature Guaranteed
                            DISTRIBUTION INSTRUCTIONS
          The assignee  should include the following for the  information of the
Servicer:
          Distribution  shall be made by check  mailed to
                                                          ----------------------
-------------------------------------------------------------------------------,
or if the aggregate  Initial  Certificate  Principal  Balance of Certificates of
this Class held by the Holder is at least $2,500,000 or the Percentage  Interest
within  such Class is 100%,  and the  Trustee  shall have  received  appropriate
wiring  instructions  in  accordance  with the  Agreement,  by wire  transfer in
immediately  available  funds  to the account of                               ,
                                                 ------------------------------
account  number              .  This  information  is provided  by the  assignee
                 ------------
named above, or its agent.
                                     B-1-6
                                    EXHIBIT C
                           SCHEDULE OF MORTGAGE LOANS
                    (A copy may be obtained from the Trustee)
                                      C-1
                                   EXHIBIT D-1
                    FORM OF INITIAL CERTIFICATION OF TRUSTEE
                                December 23, 2000
Credit Suisse First Boston Mortgage Securities Corp.
▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇  ▇▇▇▇▇
          Re:  Pooling  and   Servicing   Agreement   ("Pooling   and  Servicing
               Agreement")    relating   to   Washington    Mutual   Bank,   FA.
               Mortgage-Backed Pass-Through Certificates, Series 1999-WM4
Ladies and Gentlemen:
          In  accordance  with and subject to the  provisions of Section 2.02 of
the  Pooling and  Servicing  Agreement,  the  undersigned,  as  Trustee,  hereby
certifies that, except for the exceptions noted on the schedule attached hereto,
it has (a) received an original Mortgage Note with respect to each Mortgage Loan
listed on the Mortgage Loan Schedule and (b) received an original Mortgage (or a
certified  copy  thereof)  with  respect  to each  Mortgage  Loan  listed on the
Mortgage  Loan  Schedule  in  accordance  with  Section  2.01 of the Pooling and
Servicing  Agreement.  The Trustee has made no  independent  examination  of any
documents  contained  in each  Mortgage  File  beyond  the  review  specifically
mentioned above. The Trustee makes no  representations  as to: (i) the validity,
legality,  sufficiency,  enforceability  or  genuineness of any of the documents
delivered in accordance with Section 2.01 of the Pooling and Servicing Agreement
or any of the Mortgage Loans  identified in the Mortgage Loan Schedule,  or (ii)
the  collectibility,  insurability,  effectiveness  or  suitability  of any such
Mortgage Loan.
          The  Trustee  acknowledges  receipt of notice that the  Depositor  has
granted to the  Trustee  for the  benefit of the  Certificateholders  a security
interest  in all of the  Depositor's  right,  title and  interest  in and to the
Mortgage Loans.
          Capitalized  terms  used  herein  without  definition  shall  have the
meaning assigned to them in the Pooling and Servicing Agreement.
                                   BANK ONE, NATIONAL ASSOCIATION,
                                     as Trustee
                                   By
                                      D-1
                                   EXHIBIT D-2
                        FORM OF CERTIFICATION OF TRUSTEE
                                     [date]
Washington Mutual Bank, FA
▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇
Credit Suisse First Boston Mortgage Securities Corp.
▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇  ▇▇▇▇▇
          Re:  Pooling  and   Servicing   Agreement   ("Pooling   and  Servicing
               Agreement")    relating   to    Washington    Mutual   Bank,   FA
               Mortgage-Backed Pass-Through Certificates, Series 1999-WM4
Ladies and Gentlemen:
          In  accordance  with and subject to the  provisions of Section 2.02 of
the  above-referenced  Pooling  and  Servicing  Agreement  the  undersigned,  as
Trustee,  hereby certifies that, except for the exceptions noted on the schedule
attached  hereto,  as to each Mortgage Loan listed in the Mortgage Loan Schedule
it has reviewed the Mortgage File and has  determined  that (based solely on its
review  of each such  documents  on its face)  (i) all  documents  described  in
clauses  (i)-(v) of Section 2.01 of the Pooling and  Servicing  Agreement are in
its  possession or its agent,  (ii) such  documents have been reviewed by it and
have not been mutilated,  damaged, defaced, torn or otherwise physically altered
and such documents relate to such Mortgage Loan and (iii) each Mortgage Note has
been endorsed and each  assignment of Mortgage has been delivered as provided in
Section  2.01 of the Pooling and  Servicing  Agreement.  The Trustee has made no
independent  examination of any documents required to be delivered in accordance
with  Section  2.01 of the Pooling  and  Servicing  Agreement  beyond the review
specifically  required therein.  The Trustee makes no representations as to: (i)
the validity, legality, sufficiency, enforceability or genuineness of any of the
documents  required to be  delivered  in  accordance  with  Section  2.01 of the
Pooling and Servicing  Agreement or any of the Mortgage Loans  identified on the
Mortgage Loan Schedule, or (ii) the collectibility,  insurability, effectiveness
or suitability of any such Mortgage Loan.
          Capitalized  terms used herein  without  definition  have the meanings
ascribed to them in the Pooling and Servicing Agreement.
                                    BANK ONE, NATIONAL ASSOCIATION,
                                     as Trustee
                                    By:
                                        ----------------------------------------
                                        Authorized Representative
                                     D-2-1
                                    EXHIBIT E
                           FORM OF REQUEST FOR RELEASE
                                     [date]
To:
          In connection  with the  administration  of the Mortgage Loans held by
you as Trustee under the Pooling and Servicing Agreement dated as of December 1,
1999, among Credit Suisse First Boston Mortgage  Securities Corp., as Depositor,
Washington  Mutual Bank,  FA, as seller and  servicer,  and you, as Trustee (the
"Pooling and Servicing Agreement"), the undersigned hereby requests a release of
the Mortgage File held by you as Trustee with respect to the following described
Mortgage Loan for the reason indicated below.
▇▇▇▇▇▇▇▇▇'s Name:
Address:
Loan No.:
Reason for requesting file:
        1.      Mortgage Loan paid in full.
----            (The Servicer hereby certifies that all amounts received in
                connection  with the  Mortgage  Loan  have  been or will be
                credited to the Custodial  Account  pursuant to the Pooling
                and Servicing Agreement.)
        2.      Mortgage Loan repurchased.
----            (The Servicer hereby  certifies that the Purchase Price has
                been  credited  to the  Custodial  Account  pursuant to the
                Pooling and Servicing Agreement.)
        3.      The Mortgage Loan is being foreclosed.
----
        4.      Other.  (Describe)
----
          The undersigned acknowledges that the above Mortgage File will be held
by the  undersigned  in  accordance  with  the  provisions  of the  Pooling  and
Servicing  Agreement and will be returned,  except if the Mortgage Loan has been
paid in full or repurchased (in which case the Mortgage File will be retained by
us permanently) when no longer required by us for such purpose.
          Capitalized terms used herein shall have the meanings ascribed to them
in the Pooling and Servicing Agreement.
                                   [SERVICER]
                                   By:
                                       -----------------------------------------
                                       Name:
                                       Title:
                                      E-1
                                    EXHIBIT F
                     FORM OF INVESTOR REPRESENTATION LETTER
                                     [date]
Credit Suisse First Boston Mortgage Securities Corp.
▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇  ▇▇▇▇▇
Bank One, National Association
▇ ▇▇▇▇ ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇-▇▇▇▇
▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇ ▇▇▇▇▇-0126
          Re:  Washington   Mutual   Bank,   FA   Mortgage-Backed   Pass-Through
               Certificates, Series 1999-WM4
Ladies and Gentlemen:
          [                         ] (the "Purchaser") intends to purchase from
           -------------------------
[                               ] (the "Seller") the  Washington Mutual Bank, FA
 -------------------------------
Mortgage-Backed  Pass-Through  Certificates,  Series 1999-WM4 Class A-[1],  [2],
[3][4][5][6]7][8][9][Class R] (together, the "Certificates"), issued pursuant to
the Pooling and Servicing  Agreement  (the  "Pooling and Servicing  Agreement"),
dated  as of  December  1,  1999  among  Credit  Suisse  First  Boston  Mortgage
Securities  Corp., as Depositor (the "Company"),  Washington Mutual Bank, FA, as
seller  and  servicer,  and Bank One,  National  Association,  as  trustee  (the
"Trustee").  All terms used  herein  and not  otherwise  defined  shall have the
meanings set forth in the Pooling and Servicing Agreement.  The Purchaser hereby
certifies,  represents and warrants to, and covenants  with, the Company and the
Trustee that:
          1. The Purchaser  understands that (a) the Certificates  have not been
and will not be registered  or qualified  under the  Securities  Act of 1933, as
amended (the "Act") or any state securities law, (b) the Company is not required
to so register or qualify the  Certificates,  (c) the Certificates may be resold
only if registered  and qualified  pursuant to the  provisions of the Act or any
state   securities  law,  or  if  an  exemption  from  such   registration   and
qualification  is available,  (d) the Pooling and Servicing  Agreement  contains
restrictions regarding the transfer of the Certificates and (e) the Certificates
will bear a legend to the foregoing effect.
          2. The Purchaser is acquiring the Certificates for its own account for
investment  only  and not  with a view to or for  sale in  connection  with  any
distribution  thereof in any manner that would violate the Act or any applicable
state securities laws.
          3. The  Purchaser is (a) a  substantial,  sophisticated  institutional
investor having such knowledge and experience in financial and business matters,
and,  in  particular,  in such  matters  related  to  securities  similar to the
Certificates,  such that it is  capable  of  evaluating  the merits and risks of
investment in the  Certificates,  (b) able to bear the economic risks of such an
investment  and (c) an "accredited  investor"  within the meaning of Rule 501(a)
promulgated pursuant to the Act.
                                      F-1
          4. The Purchaser has been  furnished  with, and has had an opportunity
to review (a) a copy of the Pooling and  Servicing  Agreement and (b) such other
information  concerning the Certificates,  the Mortgage Loans and the Company as
has been  requested  by the  Purchaser  from the  Company  or the  Seller and is
relevant to the Purchaser's decision to purchase the Certificates. The Purchaser
has had any  questions  arising from such review  answered by the Company or the
Seller to the satisfaction of the Purchaser.
          5. The Purchaser has not and will not nor has it authorized or will it
authorize  any  person to (a)  offer,  pledge,  sell,  dispose  of or  otherwise
transfer any  Certificate,  any interest in any Certificate or any other similar
security to any person in any manner,  (b) solicit any offer to buy or to accept
a pledge, disposition of other transfer of any Certificate,  any interest in any
Certificate  or any other similar  security  from any person in any manner,  (c)
otherwise approach or negotiate with respect to any Certificate, any interest in
any Certificate or any other similar security with any person in any manner, (d)
make any general  solicitation  by means of general  advertising or in any other
manner or (e) take any other  action,  that (as to any of (a) through (e) above)
would  constitute a distribution  of any  Certificate  under the Act, that would
render the disposition of any Certificate a violation of Section 5 of the Act or
any state  securities law, or that would require  registration or  qualification
pursuant thereto.  The Purchaser will not sell or otherwise  transfer any of the
Certificates,  except in  compliance  with the  provisions  of the  Pooling  and
Servicing Agreement.
          6. The Purchaser:
          (a) is not an employee benefit or other plan subject to the prohibited
transaction  provisions of the Employee  Retirement Income Security Act of 1974,
as amended  ("ERISA"),  or Section 4975 of the Internal Revenue Code of 1986, as
amended (a "Plan"),  or any other person  (including  an investment  manager,  a
named  fiduciary or a trustee of any Plan) acting,  directly or  indirectly,  on
behalf of or purchasing  any  Certificate  with "plan assets" of any Plan within
the  meaning  of  the  Department  of  Labor  ("DOL")  regulation  at 29  C.F.R.
ss.2510.3-101; or
          (b) is an insurance  company,  the source of funds to be used by it to
purchase the Certificates is an "insurance  company general account" (within the
meaning of DOL Prohibited  Transaction Class Exemption  ("PTCE") 95-60), and the
purchase is being made in reliance upon the availability of the exemptive relief
afforded under Sections I and III of PTCE 95-60.
                                   Very truly yours,
                                   [Purchaser]
                                   By:
                                       -----------------------------------------
                                       Name:
                                       Title:
                                      F-2
                                    EXHIBIT G
                    FORM OF TRANSFEROR REPRESENTATION LETTER
                                     [date]
Credit Suisse First Boston Mortgage Securities Corp.
▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇  ▇▇▇▇▇
Bank One, National Association
▇ ▇▇▇▇ ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇-▇▇▇▇
▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇ ▇▇▇▇▇-0126
          Re:  Washington   Mutual   Bank,   FA   Mortgage-Backed   Pass-Through
               Certificates, Series 1999-WM4
Ladies and Gentlemen:
          In  connection  with  the  sale  by [                 ] (the "Seller")
                                               -----------------
to [                           ]  (the "Purchaser") the Washington Mutual  Bank,
    ---------------------------
FA Mortgage-Backed Pass-Through Certificates,  Series 1999-WM4 Class A-[1], [2],
[3][4][5][6][7][8][9][Class  R] (together, the "Certificates"),  issued pursuant
to the Pooling and Servicing Agreement (the "Pooling and Servicing  Agreement"),
dated  as of  December  1,  1999  among  Credit  Suisse  First  Boston  Mortgage
Securities Corp., as Depositor (the "Company"),  Washington Mutual Bank, FA., as
seller  and  servicer,  and Bank One,  National  Association,  as  trustee  (the
"Trustee"),  the  Seller  hereby  certifies,  represents  and  warrants  to, and
covenants with, the Company and the Trustee that:
          Neither  the Seller nor anyone  acting on its behalf has (a)  offered,
pledged,  sold,  disposed  of or  otherwise  transferred  any  Certificate,  any
interest in any  Certificate or any other similar  security to any person in any
manner, (b) has solicited any offer to buy or to accept a pledge, disposition or
other transfer of any Certificate,  any interest in any Certificate or any other
similar security from any person in any manner, (c) has otherwise  approached or
negotiated with respect to any  Certificate,  any interest in any Certificate or
any other  similar  security  with any  person in any  manner,  (d) has made any
general  solicitation by means of general advertising or in any other manner, or
(e) has taken any other action,  that (as to any of (a) through (e) above) would
constitute a distribution of the  Certificates  under the Securities Act of 1933
(the "Act"), that would render the disposition of any Certificate a violation of
Section  5 of the  Act or any  state  securities  law,  or  that  would  require
registration or qualification  pursuant thereto. The Seller will not act, in any
manner set forth in the foregoing sentence with respect to any Certificate.  The
Seller has not and will not sell or otherwise  transfer any of the Certificates,
except in compliance with the provisions of the Pooling and Servicing Agreement.
                                    Very truly yours,
                                    [SELLER]
                                     By:
                                         ---------------------------------------
                                         Name:
                                         Title:
                                      G-1
                                    EXHIBIT H
                FORM OF INVESTOR TRANSFER AFFIDAVIT AND AGREEMENT
STATE OF NEW YORK   )
                    :  ss.:
COUNTY OF NEW YORK  )
          [NAME OF OFFICER], being first duly sworn, deposes and says:
          1.  That he is  [Title  of  Officer]  or [Name of  Owner]  (record  or
beneficial  owner (the  "Owner")  of the Class I R  Certificates  (the  "Class R
Certificates")),  a  [savings  institution]  [corporation]  duly  organized  and
existing  under the laws of [the State of ] [the  United  States],  on behalf of
which he makes this affidavit and agreement.
          2.  That  the  Owner  (i)  is not  and  will  not  be a  "disqualified
organization" as of [date of transfer] within the meaning of Section  860E(e)(5)
of the  Internal  Revenue  Code of 1986,  as  amended  (the  "Code"),  (ii) will
endeavor  to remain  other than a  disqualified  organization  for so long as it
retains  its  ownership  interest  in the  Class R  Certificates,  and  (iii) is
acquiring  the Class R  Certificates  for its own  account or for the account of
another  Owner  from  which  it has  received  an  affidavit  and  agreement  in
substantially  the same  form as this  affidavit  and  agreement.  A  "Permitted
Transferee" is any person other than a  "disqualified  organization".  (For this
purpose,  a "disqualified  organization"  means the United States,  any state or
political  subdivision  thereof,  any  agency or  instrumentality  of any of the
foregoing  (other than an  instrumentality  all of the  activities  of which are
subject to tax and,  except for the Federal Home Loan  Mortgage  Corporation,  a
majority of whose board of directors  is not  selected by any such  governmental
entity) or any foreign government,  international  organization or any agency or
instrumentality of such foreign  government or organization,  any electing large
partnership  under  Section 775 of the Code or any rural  electric or  telephone
cooperative, or any organization (other than certain farmers' cooperatives) that
is generally exempt from federal income tax unless such  organization is subject
to the tax on unrelated business taxable income).
          3.  That the Owner is aware (i) of the tax that  would be  imposed  on
transfers of Class R Certificates to disqualified  organizations under the Code;
(ii) that such tax would be on the  transferor  (or,  with  respect to  electing
large  partnerships,  on such  partnership),  or, if such transfer is through an
agent (which person includes a broker, nominee or middleman) for a non-Permitted
Transferee,  on the agent; (iii) that the person (other than with transfers with
respect to electing large  partnerships)  otherwise  liable for the tax shall be
relieved of liability for the tax if the transferee  furnishes to such person an
affidavit  that the  transferee  is a Permitted  Transferee  and, at the time of
transfer,  such person  does not have actual  knowledge  that the  affidavit  is
false;  and (iv)  that the Class R  Certificates  may be  "noneconomic  residual
interests" within the meaning of Treasury  regulations  promulgated  pursuant to
the Code and that the transferor of a noneconomic  residual interest will remain
liable for any taxes due with respect to the income on such  residual  interest,
if a significant  purpose of the transfer was to enable the transferor to impede
the assessment or collection of tax.
          4.  That the  Owner is aware  of the tax  imposed  on a  "pass-through
entity"  holding Class R Certificates  if at any time during the taxable year of
the  pass-through  entity a non-Permitted  Transferee is the record holder of an
interest in such entity.  (For this purpose,  a "pass through entity" includes a
regulated  investment  company,  a real estate  investment trust or common trust
fund, a partnership, trust or estate, and certain cooperatives.)
                                      H-1
          5. That the Owner is aware  that the  Trustee  will not  register  the
Transfer of any Class R Certificates unless the transferee,  or the transferee's
agent,  delivers  to it an  affidavit  and  agreement,  among other  things,  in
substantially the same form as this affidavit and agreement. The Owner expressly
agrees  that it will not  consummate  any such  transfer if it knows or believes
that any of the  representations  contained in such  affidavit and agreement are
false.
          6. That the Owner has reviewed the  restrictions set forth on the face
of the Class R  Certificates  and the  provisions of Section 6.02 of the Pooling
and Servicing  Agreement under which the Class R Certificates  were issued.  The
Owner expressly  agrees to be bound by and to comply with such  restrictions and
provisions.
          7.  That  the  Owner  consents  to  any  additional   restrictions  or
arrangements that shall be deemed necessary upon advice of counsel to constitute
a reasonable  arrangement to ensure that the Class R  Certificates  will only be
owned, directly or indirectly, by an Owner that is a Permitted Transferee.
          8. That the Owner's Taxpayer Identification Number is .
          9. That the Owner is a citizen or  resident  of the United  States,  a
corporation,  partnership  or other entity created or organized in, or under the
laws of, the United States or any political subdivision thereof, or an estate or
trust whose income from sources without the United States is includable in gross
income  for  United  States  federal  income  tax  purposes  regardless  of  its
connection with the conduct of a trade or business within the United States.
          10. That no purpose of the Owner relating to the purchase of the Class
R Certificate  by the Owner is or will be to impede the assessment or collection
of tax.
          11. That the Owner has no present  knowledge  or  expectation  that it
will be unable to pay any United  States  taxes owed by it so long as any of the
Certificates remain outstanding.
          12. That the Owner has no present  knowledge  or  expectation  that it
will become  insolvent or subject to a bankruptcy  proceeding for so long as any
of the Certificates remain outstanding.
          13. The Owner hereby agrees to cooperate  with the Trustee and to take
any  action  required  of it by the  Code  or  Treasury  regulations  thereunder
(whether now or hereafter  promulgated) in order to create or maintain the REMIC
status of the Trust Fund.
          14. The Owner  hereby  agrees  that it will not take any  action  that
could endanger the REMIC status of the Trust Fund or result in the imposition of
tax on the Trust Fund  unless  counsel  for, or  acceptable  to, the Trustee has
provided  an opinion  that such action will not result in the loss of such REMIC
status or the imposition of such tax, as applicable.
          15. The Owner is not an employee  benefit or other plan subject to the
prohibited transaction provisions of the Employee Retirement Income Security Act
of 1974, as amended  ("ERISA"),  or Section 4975 of the Internal Revenue Code of
1986,  as amended (the "Code") (a "Plan"),  or any other  person  (including  an
investment manager, a named fiduciary or a trustee of any Plan) acting, directly
or indirectly,  on behalf of or purchasing any Certificate with "plan assets" of
any Plan.
                                      H-2
          IN  WITNESS  WHEREOF,  the  Owner has  caused  this  instrument  to be
executed on its behalf,  pursuant to the authority of its Board of Directors, by
its [Title of Officer] and its corporate seal to be hereunto attached,  attested
by its [Assistant] Secretary, this day of .
                                     [NAME OF OWNER]
                                     By:
                                         ---------------------------------------
                                         [Name of Officer]
                                         [Title of Officer]
[Corporate Seal]
ATTEST:
[Assistant] Secretary
          Personally appeared before me the above-named [Name of Officer], known
or proved to me to be the same person who executed the foregoing  instrument and
to be the  [Title of  Officer]  of the  Owner,  and  acknowledged  to me that he
executed  the  same as his  free  act and  deed and the free act and deed of the
Owner.
          Subscribed and sworn before me this         day of                   .
                                              -------        ------------------
                                  ----------------------------------------------
                                  NOTARY PUBLIC
                                  COUNTY OF
                                            -------------------------
                                  STATE OF
                                           -------------------------
                                  My  Commission  expires the             day of
                                                              -----------
                                                , 20   .
                                  --------------    ---
                                      H-3
                                    EXHIBIT I
                          FORM OF TRANSFER CERTIFICATE
                                     [date]
Credit Suisse First Boston Mortgage Securities Corp.
▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇
Bank One, National Association
▇ ▇▇▇▇ ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇-▇▇▇▇
▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇ ▇▇▇▇▇-0126
          Re:  Washington   Mutual   Bank,   FA   Mortgage-Backed   Pass-Through
               Certificates,  Series 1999-WM4, Class R or Series 2001-AR5, Class
               I-R (the "Certificates")
Ladies and Gentlemen:
          This letter is  delivered  to you in  connection  with the sale by [ ]
(the "Seller") to [ ] (the "Purchaser") of a % Percentage  Interest in the above
referenced  Certificates,  pursuant to Section 6.02 of the Pooling and Servicing
Agreement (the "Pooling and Servicing Agreement"), dated as of December 1, 1999,
as amended and restated as of December 1, 2001, among Credit Suisse First Boston
Mortgage  Securities Corp. as depositor (the  "Depositor"),  Bank One,  National
Association,  as trustee (the  "Trustee")  and  Washington  Mutual Bank,  FA, as
seller and servicer.  All terms used herein and not otherwise defined shall have
the meanings set forth in the Pooling and Servicing Agreement. The Seller hereby
certifies, represents and warrants to, and covenants with, the Depositor and the
Trustee that:
          1. No purpose of the Seller relating to sale of the Certificate by the
Seller to the  Purchaser  is or will be to  enable  the  Seller  to  impede  the
assessment or collection of any tax.
          2. The Seller  understands  that the  Purchaser  has  delivered to the
Trustee a transfer  affidavit  and agreement in the form attached to the Pooling
and  Servicing  Agreement as Exhibit J. The Seller does not know or believe that
any representation contained therein is false.
          3. The Seller has no actual knowledge that the proposed  Transferee is
not a Permitted Transferee.
          4. The  Seller has no actual  knowledge  that the  Purchaser  would be
unwilling  or  unable  to pay  taxes  due on its  share  of the  taxable  income
attributable to the Certificate.
          5.  The  Seller  has  conducted  a  reasonable  investigation  of  the
financial  condition  of the  Purchaser  and, as a result of the  investigation,
found that the Purchaser has  historically  paid its debts as they came due, and
found no  significant  evidence to indicate that the Purchaser will not continue
to pay its debts as they come due in the future.
                                      I-1
          6.  The  Purchaser  has   represented  to  the  Seller  that,  if  the
Certificate constitutes a noneconomic residual interest, it (i) understands that
as holder of a noneconomic  residual  interest it may incur tax  liabilities  in
excess of any cash flows  generated  by the  interest,  and (ii)  intends to pay
taxes associated with its holding of the Certificate as they become due.
                                    Very truly yours,
                                    [SELLER]
                                     By:
                                         ---------------------------------------
                                         Name:
                                         Title:
                                      I-2
                                    EXHIBIT J
                                 FORM OF ALLONGE
                                     ALLONGE
         PAY   THE   NOTE   AFFIXED   TO   THIS   ALLONGE   TO  THE   ORDER   OF
                                                        , WITHOUT RECOURSE.
--------------------------------------------------------
                                      WASHINGTON MUTUAL BANK, FA
                                      ------------------------------------------
                                               [Signature]
                                      Name:
                                             -----------------------------------
                                      Title:
                                             -----------------------------------
                                      J-1
                                    EXHIBIT K
                          FORM OF REQUEST FOR EXCHANGE
                                                                          [DATE]
----------------------
----------------------
----------------------
          Re:  Credit Suisse First Boston Mortgage Securities Corp.,  Washington
               Mutual  Bank,  FA  Mortgage  Pass-Through  Certificates,   SerieS
               2001-AR5
               -----------------------------------------------------------------
          Washington Mutual Bank, FA, as the Holder of a % Percentage Interest
of the Class Y [-1] Certificates, hereby requests the Trustee to exchange the
above-referenced Certificates for the Subclasses referred to below:
          1.   Class Y- Certificates, corresponding to the following
               uncertificated REMIC regular interests: [List numbers
               corresponding to the related loans from the Mortgage Loan
               Schedule]. The initial Certificate Principal Balance and the
               Pass-Through Rate on the Class Y- Certificates will be $ and %,
               respectively.
          2.   [Repeat as appropriate.]
          The Subclasses requested above will represent in the aggregate all of
the Uncertificated REMIC regular interests represented by the Class Y [-1]
Certificates surrendered for exchange.
          All capitalized terms used but not defined herein shall have the
meanings set forth in the Amended and Restated Pooling and Servicing Agreement,
dated as of November 1, 2001 among Washington Mutual Bank, FA, as seller
servicer, Credit Suisse First Boston Mortgage Securities Corp,. as depositor,
and Bank One, National Association, as trustee.
                                   WASHINGTON MUTUAL BANK, FA
                                   By:
                                       -----------------------------------------
                                       Name:
                                       Title:
                                      K-1
                                   SCHEDULE X
                    (A copy may be obtained from the Trustee)
                                   Schedule X
                                   SCHEDULE Y
                    (A copy may be obtained from the Trustee)
                                   Schedule Y