Document:

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                                                                    EXHIBIT 10.4

                    ASSIGNMENT OF PURCHASE AND SALE CONTRACT
                      REPLACEMENT PROPERTY - REAL PROPERTY

Re:      Exchange No.: EX-12-2930

         This Assignment of Purchase and Sale Contract (this "Purchase
Assignment") is made and entered into on ______________, by and among Tisano
Realty, Inc. ("Exchanger"), Investment Property Exchange Services, Inc., a
California corporation, as Qualified Intermediary under Exchange No. EX-12-2930
("Qualified Intermediary"), and Tower Place Joint Venture ("Seller").

                                    RECITALS

         A. Exchanger and Seller are parties to that certain Purchase and Sale
Contract dated 1/2/2002 (that agreement, as amended, is referred to as the
"Purchase Agreement"). The real property (and all improvements on the real
property) that is the subject of this transaction is described in the Purchase
Agreement and is referred to as the "Replacement Property".

         B. Exchanger desires to assign to Qualified Intermediary certain
interests and rights of Exchanger under the Purchase Agreement, as more
particularly set forth in this Purchase Assignment.

         C. The Purchase Agreement provides that Seller will cooperate with
Exchanger in a tax-deferred exchange of the Replacement Property under Section
1031 of the Internal Revenue Code (the "Exchange").

         D. Exchanger and Qualified Intermediary have executed an Exchange
Agreement (the "Exchange Agreement") in which Exchanger agrees to transfer a
Relinquished Property to Qualified Intermediary in return for Qualified
Intermediary's agreement to purchase Replacement Property and transfer the
Replacement Property to Exchanger. (Capitalized terms used in this Purchase
Assignment without definition have the meanings defined in the Exchange
Agreement.)

                                    AGREEMENT

         NOW, THEREFORE, with reference to the foregoing recitals, and in
consideration of mutual covenants and conditions hereinafter set forth and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Purchase Agreement is hereby modified and supplemented
as follows:

         1. Assignment and Assumption; Seller's Consent. Exchanger assigns to
Qualified Intermediary all of Exchanger's right, title and interest under the
Purchase Agreement, including earnest money deposits. The obligation of
Exchanger to deposit funds for the purchase of the Replacement Property, as

<PAGE>

required under the Purchase Agreement, is assigned to Qualified Intermediary.
Qualified Intermediary accepts the assignment. Subject to the provisions of this
Purchase Assignment, Qualified Intermediary assumes Exchanger's interests and
rights to acquire the Replacement Property from Seller under the Purchase
Agreement. Qualified Intermediary is substituted in place of Exchanger under the
Purchase Agreement solely for the purpose of acquiring the Replacement Property
from Seller in order to facilitate the Exchange. Seller consents to the
assignment upon the terms and conditions set forth in this Purchase Assignment.

         2. Qualified Intermediary as Buyer; Direct Deeding. Seller, Exchanger
and Qualified Intermediary will acquire the Replacement Property from Seller.
Qualified Intermediary, as buyer, instructs the Settlement Agent to record a
conveyance document transferring the Replacement Property at close directly from
Seller, as Grantor, to Exchanger, as Grantee. All bills of sale, tenant lease
assignments, general assignments and similar closing documents referenced in the
Purchase Agreement must be signed by Seller for the direct benefit of Exchanger.
None of the provisions of this Purchase Assignment will in any way detract from
the fact that Qualified Intermediary is, pursuant to this Purchase Assignment,
the buyer of the Replacement Property from Seller for federal and other
applicable state income tax purposes.

         3. Exchanger's Release and Indemnity. Exchanger releases, discharges,
holds harmless and indemnifies Qualified Intermediary from and against any
claim, demand, liability, loss, damage, cost, or expense (collectively, "Claim")
in connection with any matter relating to the Replacement Property or any term,
condition, or instrument referred to in this Purchase Assignment or otherwise
relating to the Exchange.

         4. Seller's Release. Qualified Intermediary has not made or assumed and
will not make or assume, nor will Qualified Intermediary be liable for, any
covenant, duty or obligation of Exchanger under the Purchase Agreement that may
remain in effect after the close of the transaction. Seller releases, discharges
and holds harmless Qualified Intermediary from and against any Claim in
connection with any matter relating to the Replacement Property or any term,
condition, or instrument referred to in this Purchase Assignment or otherwise
relating to the Exchange. The Seller's release does not apply to any Claim
arising from Qualified Intermediary's breach of this Purchase Assignment, gross
negligence, or willful misconduct. Seller's sole recourse will be against
Exchanger with respect to any Claim concerning the Replacement Property or any
performance, agreement, or obligation arising under the Purchase Agreement.

         5. Seller's Obligations. Seller is and will remain solely responsible
and liable to Exchanger for the performance of every warranty and obligation of
Seller with respect to the Replacement Property. Exchanger will look solely to
Seller relating to those warranties and obligations. The assignment set forth in
Section 1 above does not affect, limit, modify or impair in any way the
representations, warranties, covenants or indemnifications made by Seller or the
obligations of Seller under the Purchase Agreement, which will continue to the
benefit of Exchanger.

<PAGE>

Nothing set forth in this Purchase Agreement in any way releases Seller from any
of Seller's obligations, liabilities, indemnifications, covenants,
representations or warranties (whether express, implied in fact or implied at
law) made under the Purchase Agreement for the benefit of Exchanger, or under
any documents signed in connection with the Purchase Agreement for the benefit
of Exchanger, including, without limitation, all conveyance deeds, assignments
of contracts, assignments of leases, assignments of warranties, general
assignments, bills of sale, estoppel certificates, and escrow instructions, if
applicable (collectively, the "Collateral Documents"). Notwithstanding the
foregoing, Seller shall accept the consideration for the purchase of the
Replacement Property from Qualified Intermediary and convey title to the
Replacement Property in accordance with the terms of Section 2.

         6. Exchanger's Obligation. Exchanger is and will remain solely
responsible and liable to Seller for the performance of every warranty and
obligation of Exchanger under the Purchase Agreement. The assignment set forth
in Section 1 above does not affect, limit, modify or impair in any way the
representations, warranties, covenants or indemnifications made by Exchanger or
the obligations of Exchanger under the Purchase Agreement, which will continue
to the benefit of Seller. Nothing set forth in this Purchase Assignment in any
way releases Exchanger from any of Exchanger's obligations, liabilities,
indemnifications, covenants, representations or warranties (whether express,
implied in fact or implied at law) made under the Purchase Agreement for the
benefit of Seller, or under any documents signed in connection with the Purchase
Agreement for the benefit of Seller, including, without imitation, all
Collateral Documents.

         7. Survival. The acknowledgments and agreements of Seller, Exchanger,
and Qualified Intermediary set forth in this Purchase Assignment will survive
the closing and the recordation of any conveyance deed or other instrument in
connection therewith.

         8. Counterparts; Interpretation. This Purchase Assignment may be signed
in counterparts and may be delivered by facsimile, and each counterpart and
facsimile will be considered an original, but all of which, when taken together,
will constitute one instrument. This Purchase Assignment shall not be construed
for or against any party. The Recitals are incorporated into the Purchase
Assignment. No provision of this Agreement, including the direct deeding
provisions of Section 2, will in any way negate the fact that the Qualified
Intermediary is, pursuant to this Purchase Assignment, the seller of the
Relinquished Property to Buyer for federal income tax purposes.

         9. Litigation. If litigation is commenced between the parties regarding
this Purchase Assignment, the prevailing party will be entitled, in addition to
such other relief as may be granted, to reasonable attorney's fees and costs at
trial and on appeal.

EXCEPT AS EXPRESSLY MODIFIED OR AMENDED IN THIS PURCHASE ASSIGNMENT, ALL TERMS
AND CONDITIONS IN THE PURCHASE AGREEMENT REMAIN UNCHANGED.

<PAGE>

QUALIFIED INTERMEDIARY:

Investment Property Exchange Services, Inc., a California corporation,
as Qualified Intermediary under Exchange No. EX-12-2930

  /s/ Sybil Weatherman
---------------------------
Sybil Weatherman
Senior Exchange Coordinator

EXCHANGER(S):

Tisano Realty, Inc.

  /s/
----------------------------
By:
Its:

SELLER:

TOWER PLACE JOINT VENTURE, a
Texas joint venture

By:  Murray Income Properties I, Ltd., a
     Texas limited partnership

     By:    /s/ Mitchell Armstrong
            ----------------------------
     Name:  Mitchell Armstrong
            ----------------------------
     Title: President
            ----------------------------<PAGE>
                                                                    EXHIBIT 10.4

                    ASSIGNMENT OF PURCHASE AND SALE CONTRACT
                      REPLACEMENT PROPERTY - REAL PROPERTY

Re:      Exchange No.: EX-12-2930

         This Assignment of Purchase and Sale Contract (this "Purchase
Assignment") is made and entered into on ______________, by and among Tisano
Realty, Inc. ("Exchanger"), Investment Property Exchange Services, Inc., a
California corporation, as Qualified Intermediary under Exchange No. EX-12-2930
("Qualified Intermediary"), and Tower Place Joint Venture ("Seller").

                                    RECITALS

         A. Exchanger and Seller are parties to that certain Purchase and Sale
Contract dated 1/2/2002 (that agreement, as amended, is referred to as the
"Purchase Agreement"). The real property (and all improvements on the real
property) that is the subject of this transaction is described in the Purchase
Agreement and is referred to as the "Replacement Property".

         B. Exchanger desires to assign to Qualified Intermediary certain
interests and rights of Exchanger under the Purchase Agreement, as more
particularly set forth in this Purchase Assignment.

         C. The Purchase Agreement provides that Seller will cooperate with
Exchanger in a tax-deferred exchange of the Replacement Property under Section
1031 of the Internal Revenue Code (the "Exchange").

         D. Exchanger and Qualified Intermediary have executed an Exchange
Agreement (the "Exchange Agreement") in which Exchanger agrees to transfer a
Relinquished Property to Qualified Intermediary in return for Qualified
Intermediary's agreement to purchase Replacement Property and transfer the
Replacement Property to Exchanger. (Capitalized terms used in this Purchase
Assignment without definition have the meanings defined in the Exchange
Agreement.)

                                    AGREEMENT

         NOW, THEREFORE, with reference to the foregoing recitals, and in
consideration of mutual covenants and conditions hereinafter set forth and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Purchase Agreement is hereby modified and supplemented
as follows:

         1. Assignment and Assumption; Seller's Consent. Exchanger assigns to
Qualified Intermediary all of Exchanger's right, title and interest under the
Purchase Agreement, including earnest money deposits. The obligation of
Exchanger to deposit funds for the purchase of the Replacement Property, as

<PAGE>

required under the Purchase Agreement, is assigned to Qualified Intermediary.
Qualified Intermediary accepts the assignment. Subject to the provisions of this
Purchase Assignment, Qualified Intermediary assumes Exchanger's interests and
rights to acquire the Replacement Property from Seller under the Purchase
Agreement. Qualified Intermediary is substituted in place of Exchanger under the
Purchase Agreement solely for the purpose of acquiring the Replacement Property
from Seller in order to facilitate the Exchange. Seller consents to the
assignment upon the terms and conditions set forth in this Purchase Assignment.

         2. Qualified Intermediary as Buyer; Direct Deeding. Seller, Exchanger
and Qualified Intermediary will acquire the Replacement Property from Seller.
Qualified Intermediary, as buyer, instructs the Settlement Agent to record a
conveyance document transferring the Replacement Property at close directly from
Seller, as Grantor, to Exchanger, as Grantee. All bills of sale, tenant lease
assignments, general assignments and similar closing documents referenced in the
Purchase Agreement must be signed by Seller for the direct benefit of Exchanger.
None of the provisions of this Purchase Assignment will in any way detract from
the fact that Qualified Intermediary is, pursuant to this Purchase Assignment,
the buyer of the Replacement Property from Seller for federal and other
applicable state income tax purposes.

         3. Exchanger's Release and Indemnity. Exchanger releases, discharges,
holds harmless and indemnifies Qualified Intermediary from and against any
claim, demand, liability, loss, damage, cost, or expense (collectively, "Claim")
in connection with any matter relating to the Replacement Property or any term,
condition, or instrument referred to in this Purchase Assignment or otherwise
relating to the Exchange.

         4. Seller's Release. Qualified Intermediary has not made or assumed and
will not make or assume, nor will Qualified Intermediary be liable for, any
covenant, duty or obligation of Exchanger under the Purchase Agreement that may
remain in effect after the close of the transaction. Seller releases, discharges
and holds harmless Qualified Intermediary from and against any Claim in
connection with any matter relating to the Replacement Property or any term,
condition, or instrument referred to in this Purchase Assignment or otherwise
relating to the Exchange. The Seller's release does not apply to any Claim
arising from Qualified Intermediary's breach of this Purchase Assignment, gross
negligence, or willful misconduct. Seller's sole recourse will be against
Exchanger with respect to any Claim concerning the Replacement Property or any
performance, agreement, or obligation arising under the Purchase Agreement.

         5. Seller's Obligations. Seller is and will remain solely responsible
and liable to Exchanger for the performance of every warranty and obligation of
Seller with respect to the Replacement Property. Exchanger will look solely to
Seller relating to those warranties and obligations. The assignment set forth in
Section 1 above does not affect, limit, modify or impair in any way the
representations, warranties, covenants or indemnifications made by Seller or the
obligations of Seller under the Purchase Agreement, which will continue to the
benefit of Exchanger.

<PAGE>

Nothing set forth in this Purchase Agreement in any way releases Seller from any
of Seller's obligations, liabilities, indemnifications, covenants,
representations or warranties (whether express, implied in fact or implied at
law) made under the Purchase Agreement for the benefit of Exchanger, or under
any documents signed in connection with the Purchase Agreement for the benefit
of Exchanger, including, without limitation, all conveyance deeds, assignments
of contracts, assignments of leases, assignments of warranties, general
assignments, bills of sale, estoppel certificates, and escrow instructions, if
applicable (collectively, the "Collateral Documents"). Notwithstanding the
foregoing, Seller shall accept the consideration for the purchase of the
Replacement Property from Qualified Intermediary and convey title to the
Replacement Property in accordance with the terms of Section 2.

         6. Exchanger's Obligation. Exchanger is and will remain solely
responsible and liable to Seller for the performance of every warranty and
obligation of Exchanger under the Purchase Agreement. The assignment set forth
in Section 1 above does not affect, limit, modify or impair in any way the
representations, warranties, covenants or indemnifications made by Exchanger or
the obligations of Exchanger under the Purchase Agreement, which will continue
to the benefit of Seller. Nothing set forth in this Purchase Assignment in any
way releases Exchanger from any of Exchanger's obligations, liabilities,
indemnifications, covenants, representations or warranties (whether express,
implied in fact or implied at law) made under the Purchase Agreement for the
benefit of Seller, or under any documents signed in connection with the Purchase
Agreement for the benefit of Seller, including, without imitation, all
Collateral Documents.

         7. Survival. The acknowledgments and agreements of Seller, Exchanger,
and Qualified Intermediary set forth in this Purchase Assignment will survive
the closing and the recordation of any conveyance deed or other instrument in
connection therewith.

         8. Counterparts; Interpretation. This Purchase Assignment may be signed
in counterparts and may be delivered by facsimile, and each counterpart and
facsimile will be considered an original, but all of which, when taken together,
will constitute one instrument. This Purchase Assignment shall not be construed
for or against any party. The Recitals are incorporated into the Purchase
Assignment. No provision of this Agreement, including the direct deeding
provisions of Section 2, will in any way negate the fact that the Qualified
Intermediary is, pursuant to this Purchase Assignment, the seller of the
Relinquished Property to Buyer for federal income tax purposes.

         9. Litigation. If litigation is commenced between the parties regarding
this Purchase Assignment, the prevailing party will be entitled, in addition to
such other relief as may be granted, to reasonable attorney's fees and costs at
trial and on appeal.

EXCEPT AS EXPRESSLY MODIFIED OR AMENDED IN THIS PURCHASE ASSIGNMENT, ALL TERMS
AND CONDITIONS IN THE PURCHASE AGREEMENT REMAIN UNCHANGED.

<PAGE>

QUALIFIED INTERMEDIARY:

Investment Property Exchange Services, Inc., a California corporation,
as Qualified Intermediary under Exchange No. EX-12-2930

       /s/ Sybil Weatherman
---------------------------------------------------
Sybil Weatherman
Senior Exchange Coordinator

EXCHANGER(S):

Tisano Realty, Inc.

         /s/
---------------------------------------------------
By:
Its:

SELLER:

TOWER PLACE JOINT VENTURE, a
Texas joint venture

By:      Murray Income Properties I, Ltd., a
         Texas limited partnership

         By:      /s/ Mitchell Armstrong
                  -----------------------------------
         Name:             Mitchell Armstrong
                  -----------------------------------
         Title:            President
                  -----------------------------------

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