EXHIBIT 10.66 SIXTH AMENDMENT TO AGREEMENT FOR PURCHASE AND SALE AND JOINT ESCROW INSTRUCTIONS ----------------------------------------------- This Sixth Amendment to Agreement of Purchase and Sale and Joint Escrow Instructions (this "Sixth Amendment") is made as of September 25, 1997 by and between Kilroy Realty, L.P., a Delaware limited partnership ("Buyer") and Mission Square Partners, a California general partnership ("Seller") with respect to the following: R E C I T A L S : - - - - - - - - A. Seller and Buyer entered into that certain Agreement of Purchase and Sale and Joint Escrow Instructions providing for the sale of 3750 University Avenue, Riverside, California as amended by certain amendments to the same (collectively, the "Agreement"); B. Buyer and Seller have discussed reducing the Purchase Price by Six Hundred Thousand Dollars ($600,000.00), but the parties have not come to a final agreement regarding the same; C. Buyer and Seller anticipate that additional time will be required to complete Buyer's review of the Property and to agree upon the terms of the Purchase Price reduction; D. Seller and Buyer desire to amend the Agreement to provide for such additional time. NOW THEREFORE, in consideration of the mutual covenants and agreements herein contained and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Seller and Buyer hereby agree as follows: A G R E E M E N T : - - - - - - - - - 1. Notwithstanding anything in the Agreement to the contrary, the Contingency Date, including, but not limited to, for the purpose of Buyer obtaining the Met Consent, provided for in the Agreement is hereby extended to October 3, 1997. 2. Notwithstanding anything in the Agreement to the contrary, the Closing Date shall be deemed to be the earlier of (a) October 7, 1997 or (b) three (3) Business Days after Buyer receives the Met Consent. 3. Except as set forth in this Sixth Amendment, the provisions of the Agreement remain unmodified and in full force and effect. if any provision of this Sixth Amendment conflicts with any provision of the Agreement, the provisions of this Sixth Amendment shall prevail. 4. Any capitalized terms which are not defined in this Sixth Amendment shall have the meaning provided for in the Agreement. 5. This Sixth Amendment may be signed in counterparts, including facsimile counterparts, which, when signed by both Buyer and Seller, shall constitute a binding agreement. IN WITNESS WHEREOF, the parties have executed this Sixth Amendment as of the date first written above. "Buyer" KILROY REALTY, L.P., A Delaware limited partnership By: /s/ Tyler Rose ------------------------------------------- Name: Tyler Rose ------------------------------------- Title: S.V.P. and Treasurer ------------------------------------ "Seller" MISSION SQUARE PARTNERS, A California general partnership By: The Betty L. Hutton Title Holding Company, Inc., (formerly known as The Betty L. Hutton Company), its general partner By:/s/ Thomas C. Parker ---------------------------------------- Name: Thomas C. Parker ---------------------------------- Title: C.E.O. --------------------------------- By: BB&K Mission Square Partners, a California general partnership, its general partner By:/s/ Christopher L. Carpenter ---------------------------------------- Name: Christopher L. Carpenter ---------------------------------- Title: General Partner --------------------------------- Acknowledgment by Escrow Holder: - ------------------------------- First American Title Insurance Company hereby acknowledges the terms of this Sixth Amendment. Dated:____________, 1997 FIRST AMERICAN TITLE INSURANCE COMPANY By: -------------------------------------------- Its Authorized Agent -2-