Document:

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                                                                   Exhibit 10.39

                                                                  EXECUTION COPY
                                                                  --------------

              FIRST AMENDMENT TO RECEIVABLES FINANCING AGREEMENT
              --------------------------------------------------

     FIRST AMENDMENT TO RECEIVABLES FINANCING AGREEMENT (the "Amendment") is
                                                              ---------
made and entered into as of June 29, 2001, among AMERICREDIT DB TRUST, a
Delaware business trust (the "Borrower"), AMERICREDIT FINANCIAL SERVICES, INC.,
                              --------
a Delaware corporation, individually ("AFS") and as initial Servicer and
                                       ---
Custodian, AMERICREDIT FUNDING CORP. IV, a Delaware corporation ("AFC"),
                                                                  ---
DEUTSCHE BANK AG, NEW YORK BRANCH ("DBNY"), as agent (the "Agent") for the
                                    ----                   -----
Lenders (as defined in the Agreement referred to below), and BANK ONE, N.A., a
national banking association, as Backup Servicer and Collateral Agent.

                             W I T N E S S E T H:
                             -------------------

     WHEREAS, the Borrower, AFS, individually and as Servicer and Custodian,
AFC, the Lenders, the Agent and Bank One, N.A., as Backup Servicer and
Collateral Agent, are parties to a certain Receivables Financing Agreement dated
as of June 30, 2000 (the "Agreement"); and
                          ---------

     WHEREAS, the parties hereto desire to amend the Agreement in the manner,
and on the terms and conditions, herein provided.

     NOW, THEREFORE, in consideration of the mutual covenants herein contained,
and other good and valuable consideration, the receipt and adequacy of which are
hereby expressly acknowledged, the parties hereto agree as follows:

     1.   Definitions. Unless otherwise defined herein, all terms used herein
          -----------
which are defined in the Agreement shall have the meanings assigned thereto in
the Agreement.

     2.   Amendments to Agreement. As of the First Amendment Effective Date (as
          -----------------------
hereinafter defined), the Agreement shall be amended as follows:

          (a)  The following definitions contained in Section 1.1 of the
                                                      -----------
Agreement shall be amended as set forth below:

          "Commitment Termination Date" - The date "June 29, 2001" appearing in
           ---------------------------
          this definition shall be changed to "June 28, 2002".

          "Deficiency Percentage" - The parenthetical "(rounded upward to the
           ---------------------
          nearest 1.0%)" shall be changed to read "(rounded upward to the
          nearest one-tenth of one percent)."

          "Eligible Receivables" - Clause (xxviii) of this definition shall be
           --------------------    ---------------
          changed to read "(xxviii) that with respect to each such Receivable on
          any date of determination, not more than 180 days have elapsed since
          the date such Receivable became a Transferred Receivable,".
<PAGE>

          "Facility A Borrowing Base" - The phrase "which constitute principal
           -------------------------
          payments on the Transferred Receivables and which are "shall be
          inserted after the words "Collection Account" in clause (iii) of such
                                                           ------------
          definition.

          "Required A Holdback" - This definition shall be amended to read in
           -------------------
          its entirety as follows:

                    "Required A Holdback" means, as of any date, the sum of (a)
                     -------------------
                     the product of 11% times the Aggregate Outstanding
                     Principal Balance of Eligible Receivables in the Total
                     Receivables Pool on such date; plus (b) the product of 2%
                                                    ----
                     times the amount on deposit on such date in the Facility A
                     Subaccount of the Collection Account attributable to
                     principal payments on the Transferred Receivables; plus (c)
                                                                        ----
                     the Deficiency Amount for such date.

          "Stated Percentage" - Clause (a) of this definition shall be changed
           -----------------    ----------
          to read "(a) 6% plus".
                          ----

          (b)  Section 8.12(b) of the Agreement shall be amended (x) by
               ---------------
deleting the second sentence of such Section in its entirety and (y) by adding
at the end of the first sentence of such Section the following:  "on a quarterly
basis; provided that the requirements of this sentence shall be deemed to be
       --------
satisfied to the extent (i) the Agent is made a party to each agreed upon
procedures letter entered into by AFS and its Independent Accountants on and
after June 30, 2001 for the review of Receivables of AFS and its Affiliates to
be undertaken in conjunction with each term securitization covering all or a
portion of such Receivables, (ii) the Agent receives a copy of each such review
addressed to it, (iii) such reviews are made not less frequently than quarterly
and (iv) a statistically significant number of Transferred Receivables is
included in the Receivables so reviewed at least once in each rolling two-
quarter period."

          (c)  Section 14.1 (l) of the Agreement shall be amended by changing
               ----------------
the "B1" rating of Moody's to "Ba3" wherever the same appears in such Section.

          (d)  Section 14.1 (m) of the Agreement shall be amended by deleting
               ----------------
"220" where the same appears in such Section and inserting, in lieu thereof,
"224."

          (e)  Section 14.1(s) of the Agreement shall be amended by deleting
               ---------------
"$500,000,000" where the same appears in such Section and inserting, in lieu
thereof, "$700,000,000".

     3.   Limitations.  The amendments set forth in Section 2 above are limited
          -----------
precisely as written and shall not be deemed to (x) be a consent to any waiver
of, or modification of, any other term or condition of the Agreement, or any of
the documents referred to therein or (y) prejudice any right or rights which the
Agent or any Lender may now have or may have in the future under or in
connection with the Agreement, or any of the documents referred to therein.

                                      -2-
<PAGE>

Except as expressly amended hereby, the terms and provisions of the Agreement
shall remain in full force and effect.

     4.   Representations and Warranties.  Each of the parties hereto severally
          ------------------------------
represents and warrants that all acts, filings and conditions required to be
done and performed and to have happened (including, without limitation, the
obtaining of necessary governmental approvals) precedent to the entering into of
this Amendment to constitute this Amendment and the Agreement as amended hereby
the duly authorized, legal, valid and binding obligation of such party,
enforceable in accordance with its terms, have been done, performed and have
happened in due and strict compliance with all applicable laws.

     5.   Effectiveness.  This Amendment shall become effective on the date (the
          -------------
"First Amendment Effective Date") which is the later of (a) June 29, 2001 and
 ------------------------------
(b) the first date on which all the following conditions are satisfied:  (i)
each of the parties hereto shall have executed a counterpart hereof and
delivered the same to the Agent, and (ii) the Agent shall have received (x) an
amendment fee in the amount agreed to by AFS and the Agent, and (y) confirmation
from S&P that the effectiveness of this Amendment will not adversely affect its
"A" rating of the Advances.  Complete sets of counterparts hereof shall be
lodged with the Servicer and the Agent; and the Servicer shall promptly furnish
written notice of this Amendment to the Rating Agencies.

     6.   Governing Law.  THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
          -------------
ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

     7.   Counterparts.  This Amendment may be executed in several counterparts,
          ------------
each of which shall be regarded as the original and all of which shall
constitute one and the same agreement.

                          [Signature Pages to Follow]

                                      -3-
<PAGE>

     IN WITNESS WHEREOF, the parties have caused this Amendment to be executed
by their respective officers thereunto duly authorized as of the day and year
first above written.

                             AMERICREDIT DB TRUST
                             By: Bankers Trust (Delaware), not in its individual
                                 capacity but solely as Trustee

                             By:________________________________________________
                                 Name:
                                 Title:

                             AMERICREDIT FINANCIAL SERVICES, INC, individually
                             and as Servicer and Custodian

                             By:________________________________________________
                                 Name:
                                 Title:

                             AMERICREDIT FUNDING CORP. IV

                             By:________________________________________________
                                 Name:
                                 Title:

                                      -4-
<PAGE>

                                 DEUTSCHE BANK AG, NEW YORK BRANCH, as Agent, on
                                     behalf of itself and the Lenders

                                 By:____________________________________________
                                     Name:
                                     Title:

                                 By:____________________________________________
                                     Name:
                                     Title:

                                 BANK ONE, N.A., as Backup
                                 Servicer and Collateral Agent

                                 By:____________________________________________
                                     Name:
                                     Title:

                                      -5-<PAGE>

                                                                  EXECUTION COPY
                                                                   Exhibit 10.40

                                 AMENDMENT No. 1
                            dated as of June 27, 2001

                                      among

                           AMERICREDIT BARCLAYS TRUST,
                                   as Debtor,

                      AMERICREDIT FINANCIAL SERVICES, INC.,
                      Individually and as Collection Agent,

                         AMERICREDIT FUNDING CORP. III,
                                  Individually

                       SHEFFIELD RECEIVABLES CORPORATION,
                                   as Company,

                                       and

                                 BANK ONE, N.A.,
                 as Collateral Agent and Securities Intermediary

                                       to

                     AMENDED AND RESTATED SECURITY AGREEMENT

                           dated as of August 31, 2000
<PAGE>

          AMENDMENT NO. 1 dated as of June 27, 2001 ("Amendment No. 1"), by and
                                                      ---------------
among AMERICREDIT BARCLAYS TRUST, a Delaware business trust, as debtor (in such
capacity, the "Debtor"), AMERICREDIT FINANCIAL SERVICES, INC., a Delaware
               ------
corporation ("AmeriCredit"), individually and in its capacity as collection
              -----------
agent (in such capacity, the "Collection Agent"), AMERICREDIT FUNDING CORP. III,
                              ----------------
a Delaware corporation ("AFC III"), individually, SHEFFIELD RECEIVABLES
                         -------
CORPORATION, a Delaware corporation (the "Company") and BANK ONE, NA ("Bank
                                          -------                      ----
One"), individually and as collateral agent for the Secured Parties (in such
---
capacity, the "Collateral Agent") and as securities intermediary (in such
               ----------------
capacity, the "Securities Intermediary"), to the Amended and Restated Security
               -----------------------
Agreement dated as of August 31, 2000 (the "Security Agreement") among the
                                            ------------------
Debtor, AmeriCredit, AFC III, the Company and Bank One.

          WHEREAS, Section 9.2 of the Security Agreement permits amendment of
the Security Agreement upon the terms and conditions specified therein; WHEREAS,
the parties to the Security Agreement (the "Parties") wish to amend the Security
Agreement.

          NOW, THEREFORE, the Parties agree that the Security Agreement is
hereby amended effective as of the date hereof as follows:

     Sectiont 1.  Definitions. Each term used but not defined herein shall have
                  -----------
the meaning assigned to such term in the Security Agreement.

     Section 2.  Amendments to Section 1.1.
                 -------------------------

          (a) The definition of "Commitment Termination Date" is deleted in its
     entirety and replaced with the following:

          "Commitment Termination Date" means June 28, 2002, or such later date
           ---------------------------
          to which the Commitment Termination Date may be extended by the
          Debtor, the Agent and the Company not later than 30 days prior to the
          then current Commitment Termination Date.

          (b) Clause (xxii) of the definition of "Eligible Receivable" is
     deleted in its entirety and replaced with the following:

          "(xxii) in respect of which 210 days or less have elapsed since the
          date of its origination, or, in the case of the acquisition of
          receivables in conjunction with an optional purchase of Receivables
          from a public asset-backed securitization, in respect of which 180
          days or less have elapsed since the date of transfer to the Debtor
          pursuant to the terms of the Master Receivables Purchase Agreement."

                                       1
<PAGE>

          (c) The definition of "Termination Date" is deleted in its entirety
     and replaced with the following:

          ""Termination Date" means the earliest of (i) that Business Day
            ----------------
          designated by the Debtor to the Agent as the Termination Date at any
          time following 60 days' written notice to the Agent, (ii) the date on
          which the Termination Date is declared or automatically occurs
          pursuant to Section 6.2 hereof, (iii) the Commitment Termination Date
          or (iv) the Purchase Termination Date."

     Section 3.  Amendments to Section 5.3. The fourth sentence of Section 5.3
                 -------------------------
is amended by deleting the reference to a short-term credit rating of "A-1+"
therein and replacing it with a reference to a short-term credit rating of
"A-1".

     Section 4.  Amendments to Section 6.1.
                 -------------------------

          (a)  Section 6.1(h) is deleted in its entirety and is replaced with
     the following:

          "(h) [Intentionally Omitted]; or"

          (b)  Section 6.1(o) is amended by deleting the reference to
     "$5,000,000" therein and replacing it with a reference to "$10,000,000".

          (c)  Section 6.1(u) is amended by deleting the reference to
     "$500,000,000" therein and replacing it with a reference to "$800,000,000".

          (d)  Section 6.1(v) is deleted in its entirety and is replaced with
     the following:

          "(v) either (i) the long-term senior unsecured debt of AmeriCredit
Corp. is rated by either S&P or Moody's below B or Ba3, respectively, or (ii) if
AmeriCredit Corp. is not so rated, the Agent acting at the direction of the
Majority Owners, deems the creditworthiness of AmeriCredit Corp. to be
equivalent to a rating below B/Ba3; or"

     Section 5.  Counterparts. This Amendment No. 1 to the Security Agreement
                 ------------
may be executed in several counterparts, each of which shall be deemed an
original hereof and all of which, when taken together, shall constitute one and
the same Amendment No. 1 to the Security Agreement.

     Section 6.  Ratification of Security Agreement. Except as provided herein,
                 ----------------------------------
all provisions, terms and conditions of the Security Agreement shall remain in
full force and effect. As amended hereby, the Security Agreement is ratified and
confirmed in all respects.

                                       2
<PAGE>

     Section 7.  Entire Agreement. This Amendment No. 1 sets forth the entire
                 ----------------
agreement between the Parties with respect to the subject matter hereof, and
this Amendment No. 1 supersedes and replaces any agreement or understanding that
may have existed between the Parties prior to the date hereof in respect of such
subject matter.

                 [Remainder of page intentionally left blank]

                                       3
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Amendment No.
1 as of the date set forth on the first page hereof.

                                 AMERICREDIT BARCLAYS TRUST, as Debtor

                                 By: BANKERS TRUST (DELAWARE), not in its
                                  individual capacity but solely as Trustee

                                 By:  _______________________________
                                      Name:
                                      Title:

                                 AMERICREDIT FINANCIAL SERVICES, INC.,
                                  individually and as Collection Agent

                                 By:  _______________________________
                                      Name:
                                      Title:

                                 AMERICREDIT FUNDING CORP. III,
                                  individually

                                 By:  _______________________________
                                      Name:
                                      Title:
<PAGE>

                                       SHEFFIELD RECEIVABLES CORPORATION,
                                         as Company

                                       By:  _______________________________
                                          Name:
                                          Title:

                                       BANK ONE, N.A.,
                                         as Collateral Agent and as Securities
                                         Intermediary

                                       By:  _______________________________
                                          Name:
                                          Title:

ACKNOWLEDGED AND AGREED

BARCLAYS BANK PLC,

By:  _______________________________
     Name:
     Title:

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