<PAGE>

                                                                   EXHIBIT. 10.6

                       FIFTH AMENDMENT TO CONTRACT OF SALE


         This Fifth Amendment to Contract of Sale is made and entered into as of
the 21st day of October, 2004, by and between COOK, INC., a Florida corporation
("Seller"), and SILVERLEAF RESORTS, INC., a Texas corporation ("Purchaser").

                               WITNESSETH

         WHEREAS, on or about February 12, 2004, Seller and Purchaser entered
into that certain Contract of Sale pursuant to which Seller agreed to sell and
Purchaser agreed to purchase certain tracts of land containing approximately 5.3
acres, more or less, situated in Davenport, Polk County, Florida, being more
particularly described in the Contract of Sale (the "Property"); and

         WHEREAS, on or about March 18, 2004, Seller and Purchaser entered into
a certain First Amendment to Contract of Sale; and

         WHEREAS, on or about March 22, 2004, Seller and Purchaser entered into
a certain Second Amendment to Contract of Sale; and

         WHEREAS, on or about April 27, 2004, Seller and Purchaser entered into
a certain Third Amendment to Contract of Sale; and

         WHEREAS, on or about October 15, 2004, Seller and Purchaser entered
into a certain Fourth Amendment to Contract of Sale (the Contract of Sale as
amended is hereinafter referred to as the "Contract"); and

         WHEREAS, Seller and Purchaser desire to further amend the Contract in
order to extend the deadline for closing the Contract and to otherwise modify
the terms and conditions of the Contract as follows;

         NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, and other good and valuable consideration, the receipt,
accuracy and sufficiency of which is hereby acknowledged, Seller and Purchaser
hereby agree as follows:

         1. Notwithstanding anything to the contrary contained in the Contract,
Seller and Purchaser hereby agree that the deadline for closing of the Contract,
which is presently October 22, 2004, is hereby extended to November 1, 2004;
provided, however, the effective date of closing, for purposes of: (a) all
prorations, (b) the date of the Note to be executed and delivered by Purchaser
to Seller at closing, and (c) the commencement of interest accrual on the Note,
shall be October 22, 2004.

         2. Notwithstanding the execution hereof by Seller and Purchaser, all
rights and remedies of Seller and Purchaser under the Contract are hereby
preserved including, without limitation, Purchaser's right to obtain a second
extension of the deadline for closing as set forth in Article IX of the
Contract, and the rights and obligations of the parties, if any, with respect to
the agreements between Interval International and Seller.

         Except as specifically set forth above, all terms and conditions of the
Contract shall remain in full force and effect. All capitalized terms not
otherwise defined herein shall have the meaning given to such terms in the
Contract.

         IN WITNESS WHEREOF, the undersigned have executed this Amendment as of
the date and year first above written.

                                   SELLER:

                                   COOK, INC., a Florida corporation


                                   By:   /S/ DANIEL P. BOSS
                                         ---------------------------------------
                                   Name: Daniel P. Boss
                                   Its:  President

                                   PURCHASER:

                                   SILVERLEAF RESORTS, INC., a Texas corporation


                                   By:   /S/ HARRY J. WHITE, JR.
                                         ---------------------------------------
                                   Name: Harry J. White, Jr.
                                   Its:  CFO