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                                                                   EXHIBIT 10.51

                        SUPPLEMENTAL AGREEMENT REGARDING
                     ASSIGNMENT OF NOTE, LOAN AGREEMENT AND
                    SECURITY AGREEMENT AS COLLATERAL SECURITY

         This Supplemental Agreement (the "Agreement") is by and among BINGHAM
FINANCIAL SERVICES CORPORATION, a Michigan corporation ("Assignor") whose
address is 260 E. Brown Street, Suite 200, Birmingham, Michigan, 48009, and SUN
COMMUNITIES OPERATING LIMITED PARTNERSHIP, a Michigan limited partnership whose
address is 31700 Middlebelt Road, Suite 145, Farmington Hills, Michigan, 48334
("Assignee").

                                    RECITALS

         A.       Effective on December 13, 1999, Assignor assigned to Assignee
that certain promissory note in the original principal amount of $100,000.00
executed as of December 13, 1999 by BLOOMFIELD SERVICING COMPANY, LLC, as maker
("BSC"), in favor of Assignor (the "BSC Note"). The BSC Note is evidenced by a
Loan Agreement dated December 13, 1999 (the "BSC Loan Agreement") and is secured
by a security agreement (the "BSC Security Agreement") dated December 13, 1999.
Copies of the BSC Note, the BSC Loan Agreement and the BSC Security Agreement
are attached hereto as Exhibit A.

         B.       Assignor executed and delivered to Assignee a Demand
Promissory Note in the original principal amount of $10,000,000 dated March 30,
1999 and a Second Amended Demand Promissory Note in the original principal
amount of $50,000,000 dated December 13, 1999 and Assignor previously executed
and delivered to Sun Communities, Inc., a Term Promissory Note in the original
principal amount of $4,000,000 dated September 30, 1997, which was assigned and
delivered to Assignee by Sun Communities, Inc. on December 31, 1997
(collectively the "Assignor Notes").

         C.       Assignor has entered into or may in the future enter into
various agreements with Assignee, pursuant to which Assignor may have various
contractual, indemnification, warranty and/or other obligations to Assignee (the
"Contractual Obligations").

         D.       As collateral security for the payment of all amounts due to
Assignee by Assignor pursuant to the Assignor Notes (as they may be amended,
renewed, extended, modified or refinanced from time to time), to secure all
Contractual Obligations of Assignor to Assignee and to secure all other
obligations of any nature now or in the future owing from Assignor to Assignee
(hereinafter collectively referred to as the "Obligations"), Assignor delivered
to Assignee effective December 13, 1999, the BSC Note, the BSC Loan Agreement
and the BSC Security Agreement (collectively the "Collateral Documents").

         E.       Assignor desires to reflect herein its agreement with respect
to its previous delivery of the Collateral Documents.

         NOW, THEREFORE, in consideration of the foregoing recitals, the mutual
covenants and



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agreements hereinafter set forth, and other good and valuable consideration, the
receipt and adequacy of which are hereby acknowledged, the parties hereto hereby
agree as follows:

         1.       ASSIGNMENT TO ASSIGNEE. Assignor acknowledges that it intended
its delivery of the Collateral Documents as an assignment to Assignee, as
collateral security for the Obligations, of all right, title and interest of
Assignor in, to and under the Collateral Documents.

         2.       DISTRIBUTIONS. Assignor agrees that any and all amounts
received under the Collateral Documents shall be paid immediately to Assignee in
reduction of the Obligations.

         3.       FINANCING STATEMENTS. Assignor shall execute and deliver to
Assignee, at Assignor's request, Uniform Commercial Code financing statement
amendments to reflect the assignments of Assignor's interest under the
Collateral Documents.

         4.       FURTHER ASSURANCES. Assignor shall, at any time and from time
to time, upon the written request of either Assignee, execute and deliver such
further documents and do such further acts and things as either Assignee may
reasonably request to effect the purposes of this Agreement, including, without
limitation, noting on the original BSC Note that Assignee is the holder of such
notes.

         5.       SECTION HEADINGS. Section headings in this Agreement are
inserted merely for convenience and shall not modify the terms of this Agreement
in any respect.

         6.       APPLICABLE LAW. This Agreement shall be governed by and
construed in accordance with the laws of the State of Michigan.

         7.       SUCCESSORS AND ASSIGNS. All of the terms contained herein
shall survive the consummation of the transactions contemplated herein, and
shall be binding upon and inure to the benefit of and be enforceable by and
against, the parties hereto and their respective successors, assigns, heirs at
law, legal representatives and estates.

         8.       AMENDMENT. This Agreement and any other documents executed in
connection herewith may only be amended or modified, and any of the terms,
conditions, covenants, representations or warranties contained herein may only
be waived, by a written instrument duly executed by the parties hereto.

         9.       COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall be considered one and the same agreement.

                            [signature page attached]


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         IN WITNESS WHEREOF, the parties hereto have executed this Agreement
effective as of December 13, 1999.

                            ASSIGNOR:

                            BINGHAM FINANCIAL SERVICES
                            CORPORATION, a Michigan corporation


                            By:      /s/ Ronald A. Klein
                               ------------------------------------------------
                               Its:     President and Chief Executive Officer
                                   --------------------------------------------


                            ASSIGNEE:

                            SUN COMMUNITIES OPERATING
                            LIMITED PARTNERSHIP, a Michigan
                            limited partnership

                            By:  Sun Communities, Inc., a Maryland
                                     Corporation
                            Its:  General Partner

                            By:      /s/ Gary A. Shiffman
                                 ---------------------------------------------
                            Its:     President and Chief Executive Officer
                                 ---------------------------------------------