Document:

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                                                                    EXHIBIT 10.4

                                Irrevocable Proxy

         The undersigned Stockholder of Advanced Communication Systems, Inc., a
Delaware corporation (the "Company"), hereby appoints and constitutes The Titan
Corporation, a Delaware corporation ("Acquiror"), the attorneys and proxies of
the undersigned, with full power of substitution and resubstitution, to the full
extent of the undersigned's voting rights with respect to (a) the outstanding
shares of common stock, par value $.01 per share, of the Company (the "Company
Common Stock") or any other capital stock of the Company (collectively with the
Company Common Stock, the "Capital Stock") owned of record by the undersigned as
of the date of this proxy, which shares are specified on the final page of this
proxy, and (b) any and all other shares of Capital Stock of the Company which
the undersigned may acquire on or after the date hereof, provided that this
proxy automatically shall be revoked with respect to any shares of Capital Stock
that are sold, transferred or otherwise disposed of by the undersigned in
accordance with the Company Stockholders Agreement (as hereinafter defined)
("Transferred Stock") effective as of the date of such sale, transfer or other
disposition ("Date of Disposition"). Upon the execution hereof, all prior
proxies given by the undersigned with respect to any of the Capital Stock are
hereby revoked, and the undersigned agrees that no subsequent proxy will be
given with respect to the voting of any of the Capital Stock (other than
Transferred Stock after the Date of Disposition given by the purchaser,
transferee or other beneficiary of such other disposition with respect to such
stock) except to the extent that such proxies do not prevent the voting of this
proxy in favor of the transactions described herein.

         This proxy is coupled with an interest and irrevocable. This proxy is
granted (i) in connection with the execution and delivery of the Company
Stockholders Agreement, dated as of the date hereof, among Acquiror and the
undersigned (the "Company Stockholders Agreement") and (ii) in consideration of
Acquiror entering into the Agreement and Plan of Merger, dated as of the date
hereof, among Acquiror, A T Acquisition Corp., a Delaware corporation (the
"Merger Sub") and the Company (the "Merger Agreement").

         The proxy named above (and its successors) will, prior to the
Termination Date (as hereinafter defined), be empowered, and may exercise this
proxy, to vote the Capital Stock at any meeting of the Stockholders of the
Company, however called, or in connection with any solicitation of written
consents from Stockholders of the Company, called or solicited, as the case may
be, for the purpose of voting on the Merger Agreement and the transactions
contemplated thereby in favor of the approval and adoption of the Merger
Agreement and the approval of the merger contemplated thereby, and in favor of
each of the other actions contemplated by the Merger Agreement. The undersigned
may vote the Capital Stock on all other matters.

         This proxy shall be binding upon the representatives, successors and
permitted assigns of the undersigned.

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         If any provision of this proxy or any part of any such provision is
held under any circumstances to be invalid or unenforceable in any jurisdiction,
then (a) such provision or part thereof shall, with respect to such
circumstances and in such jurisdiction, be deemed amended to conform to
applicable laws so as to be valid and enforceable to the fullest possible
extent, (b) the invalidity or unenforceability of such provision or part thereof
under such circumstances and in such jurisdiction shall not affect the validity
or enforceability of such provision or part thereof under any other
circumstances or in any other jurisdiction, and (c) the invalidity or
unenforceability of such provision or part thereof shall not affect the validity
or enforceability of the remainder of such provision or the validity or
enforceability of any other provision of this proxy. Each provision of this
proxy is separable from every other provision of this proxy, and each part of
each provision of this proxy is separable from every other part of such
provision.

         This proxy and the rights contained herein shall terminate upon the
termination of the Company Stockholders Agreement as provided therein (the
"Termination Date").

Date:  December 9, 1999

                                    /s/ Thomas A. Costello
                                    -------------------------------
                                    Thomas A. Costello

                                    /s/ Margaret M. Costello
                                    -------------------------------
                                    Margaret M. Costello

                                    Number of shares of common stock and other
                                    capital stock of the Company owned of record
                                    and beneficially as of the date of this
                                    proxy: 847,500

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                                                                    EXHIBIT 10.3

                            PROCEEDS ESCROW AGREEMENT

         Agreement entered on the 25th day of January, 1999 by and among
Transition Auto Finance III, Inc. ("Issuer"), Great Nation Investment
Corporation ("Dealer"), and Texas Community Bank, a National Association, as
defined by Section 3(a)(6) of the Securities and Exchange Act of 1934, (the
"Escrow Agent").

         WHEREAS, with the assistance of Dealer, the Issuer proposes to offer
and sell up to $20,000,000 aggregate principal amount of its Secured Notes (the
"Notes") to be issued under a Trust Indenture between the Issuer and Trust
Management Inc. Trustee (the "Trustee").

         NOW, THEREFORE, the parties hereto hereby agree as follows:

       1. The Escrow Agent agrees to act as escrow agent in connection with the
offering and sale of Notes and, as such, to establish an appropriate account and
to receive the proceeds from the sale of the Notes for deposit therein until the
earlier of the termination of this Agreement or the termination of the offering
and sale of the Notes (the "Termination Date").

       2. Checks or other items for the payment of all or a part of the purchase
price of the Notes (all such items together with all proceeds thereof, the
"Escrowed Property") shall be payable to Escrow Agent and delivered daily to
Escrow Agent. The Escrow Agent will credit the proceeds to an escrow cash
account (the "Escrow Account") to be held by it under the terms of this
Agreement subject to Rule 15c2-4 under the Securities Act of 1934. All
subscribers' checks or other items for the payment of the purchase price of
Notes shall be transmitted by Dealer to the Escrow Agent by noon of the next
business day upon receipt by Dealer.

       3. The Escrowed Property, together with all interest earned thereon,
shall be held by the Escrow Agent until the earlier of (a) the time that the
Escrow Agent has received proceeds from the sale of the Notes in the aggregate
principal amount of $250,000, or more, or (b) the date of March 31, 2000 at
which time the escrow will terminate.

       4. Upon termination of the escrow, the Escrow Agent shall release the
Escrowed Property, together with all interest earned thereon to be distributed
to either (a) the Issuer, or such other party or parties, as required to carry
out the purpose of the Note offering if the minimum amount of the Notes have
been sold within the required time period described above, or (b) the
subscribers if the minimum amount of Notes have not been sold within such
period.

       5. If at any time to the completion of this escrow said Escrow Agent is
advised by the appropriate securities or state agency that the registration to
sell said notes has been revoked, said Escrow Agent shall thereupon return all
funds and the interest earned thereon to the respective subscribers.

       6. Escrow Agent shall deposit all funds received in insured accounts such
that each Investor that deposits funds is insured to the maximum amount allowed
under FDIC regulations, irrespective of the aggregate amount of funds received
from all Investors. The Escrow Agent shall invest such collected funds deposited
in the Escrow Account in short term investments to the extent permitted by the
Texas Banking Commission, provided however, that any such funds held subject to
any minimum escrow contingency shall be invested subject to Rule 15c2-4. The
Escrow Agent shall in

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no event be liable for any loss resulting from any change in interest rates
applicable to funds so invested.

         Interest on funds invested pursuant to this Section shall accrue from
the date of investment of such funds until such funds are released from escrow
pursuant to paragraph 4.

       7. The Escrow Agent's and Dealer's obligations and duties in connections
herewith are confined to those specifically enumerated in this Agreement. The
Escrow Agent and Dealer shall not be in any manner liable or responsible for the
sufficiency, correctness, genuineness or validity of any instruments received by
or deposited with them or with reference to the form of execution thereof, or
the identity, authority, or rights of any person executing, delivering, or
depositing same, and neither the Escrow Agent nor the Dealer shall be liable for
any loss that may occur by reason of forgery, false representation or the
exercise of their discretion in any particular manner or for any other reason,
except for their own gross negligence or willful misconduct.

       8. Escrow Agent shall receive compensation for its services as set forth
in the separate schedule of fees as made a part hereof by reference.

       9. The Escrow Agent may act pursuant to the written advice of counsel
with respect to any matter relating to this Escrow Agreement and shall not be
liable for any action taken or omitted in accordance with such advice.

      10. The Escrow Agent (and any other successor escrow agent) may at any
time resign as such by delivering all of the Escrowed Property to the successor
escrow agent jointly designated by the other parties hereto in writing, or to
any court of competent jurisdiction, whereupon the Escrow Agent shall be
discharged of and from any and all further obligations arising in connection
with this Escrow Agreement. The resignation of the Escrow Agent will take effect
on the earlier of (a) the appointment of a successor (including a court of
competent jurisdiction), or (b) the day which is thirty (30) days after the date
of delivery of its written notice of resignation to the other parties hereto. If
at that time the Escrow Agent has not received a designation of a successor
escrow agent, the Escrow Agent's sole responsibility after that time shall be to
safekeep the Escrowed Property until receipt of a designation of successor
escrow agent or a written disposition instruction by the Issuer and Dealer or a
final order of a court of competent jurisdiction.

      11. If any controversy arises between the parties hereto or with any third
person, the Escrow Agent shall not be required to determine the same or to take
any action but may await the settlement of any such controversy by final
appropriate legal proceeding, or otherwise as the Escrow Agent may require, or
the Escrow Agent may, in its discretion, institute such appropriate interpleader
or other proceedings in connection therewith as it may deem proper,
notwithstanding anything in this Agreement to the contrary. In any such event,
the Escrow Agent shall not be liable for interest or damages to the Issuer or
subscribers. In the event Escrow Agent should institute, or be named as a party
in, any legal proceedings to determine the lawful owner of the Escrowed
Property, Escrow Agent shall be entitled to recover from the contending parties
to said legal proceedings, reasonable attorney's fees and expenses which shall
be incurred by Escrow Agent in said proceedings.

      12. This Escrow Agreement shall be binding upon and inure solely to the
benefit of the parties hereto and their respective successors and assigns,
heirs, administrators, and representatives

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and shall not be enforceable by or inure to the benefit of any third party
except as provided in Section 10 with respect to a resignation by the Escrow
Agent. No party may assign any of its rights or obligations under this Escrow
Agreement without the written consent of the other parties. This Escrow
Agreement shall be construed in accordance with and governed by the laws of the
State of Texas with regard to conflict of law principals.

      13. This Escrow Agreement may only be modified in writing by all of the
parties hereto, and no waiver hereunder shall be effective unless in writing
signed by the party to be charged.

         IN WITNESS WHEREOF, the parties hereto have executed this agreement as
of the day and year first above written.

                                    DEALER:

                                    GREAT NATION INVESTMENT CORPORATION

                                    By:
                                       ----------------------------------------

                                    Date:
                                         --------------------------------------

Attest:
        -----------------------
                                    ISSUER:

                                    TRANSITION AUTO FINANCE III, INC.

                                    By:
                                       ----------------------------------------

                                    Date:
                                         --------------------------------------

Attest:
        -----------------------

                                    ESCROW AGENT:
                                    TEXAS COMMUNITY BANK, A National Association

                                    By:
                                       ----------------------------------------

                                    Date:
                                         --------------------------------------
Attest:
        -----------------------

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