<PAGE>

                                                                     EXHIBIT 4.4

                   ASSUMPTION AGREEMENT AND FIRST AMENDMENT TO
                      CONTRIBUTION AND SERVICING AGREEMENT


     This ASSUMPTION AGREEMENT AND FIRST AMENDMENT TO CONTRIBUTION AND SERVICING
AGREEMENT (the "Agreement") dated as of January 31, 2001 is entered into among
Conseco Finance Lease 2000-1, LLC, a Delaware limited liability company (the
"Issuer"), Green Tree Lease Finance II, Inc., a Minnesota corporation (the
"Contributor"), Conseco Finance Vendor Services Corporation, a Delaware
corporation (in its individual capacity, "Vendor Services," and in its capacity
as Servicer, the "Servicer"), Wells Fargo Bank Minnesota, National Association
(the "Trustee"), WFFLI Lease Finance 2000-1, LLC, a Delaware limited liability
company (the "Successor Issuer"), WFFLI Lease Finance II, LLC, a Delaware
limited liability company (the "Successor Contributor"), Wells Fargo Financial
Leasing, Inc., an Iowa corporation (the "Successor Servicer"), and Bank One,
National Association, a national banking association ("Successor Trustee").

     WHEREAS, the Issuer, the Contributor, Vendor Services (both individually
and in its capacity as the Servicer) and the Trustee are parties to a
Contribution and Servicing Agreement dated as of July 1, 2000 (the "Contribution
and Servicing Agreement").

     WHEREAS, pursuant to an Asset Purchase Agreement dated as of December 8,
2000 by and among the Successor Servicer, Conseco, Inc., Conseco Finance Corp.,
Vendor Services, Contributor, Green Tree Lease Finance 1998-1, LLC and the
Issuer (the "Purchase Agreement"), Successor Servicer has agreed to purchase
substantially all of the assets and certain liabilities of Vendor Services and
to assume all of the obligations of Vendor Services as the Servicer under the
Contribution and Servicing Agreement.

     WHEREAS, pursuant to the Purchase Agreement, the Successor Servicer will
cause the Successor Contributor, a limited liability company of which the
Successor Servicer is the sole member, to purchase substantially all of the
assets of the Contributor and to assume all of the obligations of the
Contributor under the Contribution and Servicing Agreement.

     WHEREAS, pursuant to the terms of a Supplemental Indenture, dated as of the
date hereof, to the Indenture dated as of July 1, 2000 between the Issuer and
the Trustee relating to the 6.844% Lease-Backed Notes, Class A-1, 7.250%
Lease-Backed Notes, Class A-2, 7.360% Lease-Backed Notes, Class A-3, 7.480%
Lease-Backed Notes, Class A-4, 7.690% Lease-Backed Notes, Class B, 7.880%
Lease-Backed Notes, Class C and 8.560% Lease-Backed Notes, Class D, of the
Issuer (as so supplemented, the "Indenture"), the Successor Issuer shall succeed
as issuer under the Indenture and the Successor Trustee shall succeed as trustee
under the Indenture.

     WHEREAS, pursuant to the terms of the Contribution and Servicing Agreement,
neither the Contributor nor the Servicer shall permit any other Person to become
the successor to its respective business unless certain conditions set forth in
the Contribution and Servicing Agreement are satisfied, including the
requirement that any such successor shall execute an assumption agreement
assuming the obligations of the Contributor or the Servicer, as the case may be,
under the Contribution and Servicing Agreement.
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     WHEREAS, the Contributor and the Servicer have furnished the Issuer and the
Trustee with (i) a certificate of a Responsible Officer and an Opinion of
Counsel stating that the agreements of assumption by the Successor Contributor
and the Successor Servicer contained herein comply with Sections 6.2 and 7.2,
respectively, of the Contribution and Servicing Agreement and that all
conditions precedent in the Contribution and Servicing Agreement relating to
such successions have been complied with; and (ii) an Opinion of Counsel stating
that all financing statements and continuation statements and amendments have
been executed and filed that are necessary to preserve and protect the interest
of the Issuer in the Trust Assets.

     WHEREAS, the parties hereto desire to amend certain provisions of the
Contribution and Servicing Agreement simultaneously with the Successor
Contributor and the Successor Servicer entering into such agreements of
assumption.

     WHEREAS, pursuant to Section 10.1(a) of the Contribution and Servicing
Agreement, the Contribution and Servicing Agreement may be amended without the
consent of any of the Noteholders (i) to cure any ambiguity contained therein,
(ii) to correct or supplement any provisions in the Contribution and Servicing
Agreement that may be inconsistent with any other provision therein; or (iii) to
make any other provisions with respect to matters or questions arising under the
Contribution and Servicing Agreement that are not inconsistent with the
provisions thereof; provided, however, that such action shall not, as evidenced
by an Opinion of Counsel, adversely affect in any material respect the interests
of the Noteholders.

     WHEREAS, an Opinion of Counsel has been delivered stating that the
amendments to the Contribution and Servicing Agreement contained herein shall
not adversely affect in any material respect the interests of the Noteholders.

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


                                    ARTICLE I

                AMENDMENT TO CONTRIBUTION AND SERVICING AGREEMENT

     Section 1.1. Defined Terms. Certain definitions set forth in Section 1.1 of
the Contribution and Servicing Agreement are hereby amended to read as follows:

          Transfer Agreement: The Transfer Agreement, dated as of July 1, 2000,
     between Vendor Services and the Contributor, as the same may be amended or
     supplemented from time to time.

          Vendor Services: Conseco Finance Vendor Services Corporation, a
     Delaware corporation, or its successor in interest."

     Section 1.2. Organizational Representations. Throughout the Contribution
and Servicing Agreement, all references to a "corporation" shall be deemed to
include a limited liability company; all references to "corporate action" shall
be deemed to include the actions of a limited liability company; all references
to "incorporated" shall be deemed to include being


                                      -2-
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organized as a limited liability company; all references to "articles of
incorporation" or "bylaws" shall be deemed to include the equivalent
organizational documents of a limited liability company; all references to
"stockholder" or "stockholders" shall be deemed to include a member or members
of a limited liability company; the reference in Section 2.4(a) to the
Contributor's good standing "under the laws of the State of Minnesota" shall be
revised to "under the laws of its jurisdiction of organization"; and any such
other changes shall be deemed to have been made as are necessary to allow a
limited liability company to serve as the Contributor under the Contribution and
Servicing Agreement to the same extent as it would be able to serve if it were
organized as a corporation.


                                   ARTICLE II

                      ASSIGNMENT AND ASSUMPTION AGREEMENTS

     Section 2.1. Successor Contributor. The Contributor hereby grants, assigns,
transfers and conveys to the Successor Contributor its entire right, title and
interest in, to and under the Contribution and Servicing Agreement and Related
Documents. The Successor Contributor hereby accepts the foregoing assignment and
hereby assumes and agrees to perform all of the obligations of the Contributor
under the Contribution and Servicing Agreement and each of the Related
Documents. The Successor Contributor further agrees to indemnify, defend and
hold harmless the Contributor against and from any loss, liability or expense
arising in connection with the Successor Contributor's failure to perform such
obligations on and after the date hereof.

     Section 2.2. Assumption of Successor Servicer. The Servicer hereby grants,
assigns, transfers and conveys to the Successor Servicer its entire right, title
and interest in, to and under the Contribution and Servicing Agreement and
Related Documents. The Successor Servicer hereby accepts the foregoing
assignment and hereby assumes and agrees to perform all of the obligations of
the Servicer under the Contribution and Servicing Agreement and each of the
Related Documents. The Successor Servicer further agrees to indemnify, defend
and hold harmless the Servicer against and from any loss, liability or expense
arising in connection with the Successor Servicer's failure to perform such
obligations on and after the date hereof.

     Section 2.3. Notice of Successor Servicer. The Successor Trustee hereby
agrees to give prompt written notice of appointment of the Successor Servicer as
the Servicer under the Contribution and Servicing Agreement to the Noteholders.


                                   ARTICLE III

                                  MISCELLANEOUS

     Section 3.1. Defined Terms. Defined terms used herein and not otherwise
defined herein shall have the meanings assigned to them in the Contribution and
Servicing Agreement or, if not defined therein, in the Indenture.

     Section 3.2. Ratification of Contribution and Servicing Agreement. Except
as expressly amended by this Agreement, the Contribution and Servicing Agreement
is in all respects ratified


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and confirmed and all the terms, conditions and provisions thereof shall remain
in full force and effect.

     Section 3.3. Entire Agreement. This Agreement (including the exhibits,
schedules and other documents referred to herein) contains the entire
understanding between the parties hereto with respect to the subject matter
hereof and supersedes any prior understandings, agreements or representations,
written or oral, relating to the subject matter hereof.

     Section 3.4. Counterparts. This Agreement may be executed in separate
counterparts, each of which will be an original and all of which taken together
shall constitute one and the same agreement, and any party hereto may execute
this Agreement by signing any such counterpart.

     Section 3.5. Severability. Whenever possible, each provision of this
Agreement shall be interpreted in such a manner as to be effective and valid
under applicable law but if any provision of this Agreement is held to be
invalid, illegal or unenforceable under any applicable law or rule, the
validity, legality and enforceability of the other provision of this Agreement
will not be affected or impaired thereby.

     Section 3.6. Modification, Amendment, Waiver or Termination. No provision
of this Agreement may be modified, amended, waived or terminated except by an
instrument in writing signed by the parties to this Agreement. No course of
dealing between the parties will modify, amend, waive or terminate any provision
of this Agreement or any rights or obligations of any party under or by reason
of this Agreement.

     Section 3.7. Headings. The headings and any table of contents contained in
this Agreement are for reference purposes only and shall not in any way affect
the meaning or interpretation of this Agreement.

     Section 3.8. Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF MINNESOTA WITHOUT REGARD
TO THE PRINCIPLES OF CONFLICTS OF LAWS THEREOF AND THE OBLIGATIONS, RIGHTS AND
REMEDIES OF THE PARTIES UNDER THIS AGREEMENT SHALL BE DETERMINED IN ACCORDANCE
WITH SUCH LAWS.

     Section 3.9. Further Assurances. Each party agrees that at any time, and
from time to time, it will do all such things and execute and deliver all such
instruments, assignments, releases, financing statements, continuation
statements, other documents and assurances as any other party reasonably deems
necessary or desirable to carry out the intent, purpose and conditions of this
Agreement, the Related Documents and the transactions contemplated hereby and
thereby.


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     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed, all as of the first day and year first written above.


                                      CONSECO FINANCE LEASE 2000-1, LLC


                                      By: /s/ Brian F. Corey
                                          --------------------------------------
                                          Name: Brian F. Corey
                                          Title: Senior Vice President and
                                                 Secretary



                                      GREEN TREE LEASE FINANCE II, INC.


                                      By: /s/ Brian F. Corey
                                          --------------------------------------
                                          Name: Brian F. Corey
                                          Title: Senior Vice President and
                                                 Secretary



                                      CONSECO FINANCE VENDOR SERVICES
                                      CORPORATION

                                      By: /s/ Brian F. Corey
                                          --------------------------------------
                                          Name: Brian F. Corey
                                          Title: Senior Vice President and
                                                 Secretary



                                      WELLS FARGO BANK MINNESOTA, National
                                      Association, not in its individual
                                      capacity, but solely as Trustee


                                      By: /s/ Marianna C. Stershic
                                          --------------------------------------
                                          Name: Marianna C. Stershic
                                          Title: Vice President


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                                      WFFLI LEASE FINANCE 2000-1, LLC


                                      By: /s/ Steve R. Wagner
                                          --------------------------------------
                                          Name: Steve R. Wagner
                                          Title: President



                                      WFFLI LEASE FINANCE II, LLC


                                      By: /s/ Steve R. Wagner
                                          --------------------------------------
                                          Name: Steve R. Wagner
                                          Title: President



                                      WELLS FARGO FINANCIAL LEASING, INC.


                                      By: /s/ Steve R. Wagner
                                          --------------------------------------
                                          Name: Steve R. Wagner
                                          Title: Vice President



                                      BANK ONE, NATIONAL ASSOCIATION, not in its
                                      individual capacity, but solely as
                                      Successor Trustee


                                      By: /s/ Chris Holly
                                          --------------------------------------
                                          Name: Chris Holly
                                          Title: Assistant Vice President


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