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                                                                   Exhibit 10.34

                       HIGHWAYMASTER COMMUNICATIONS, INC.

                             STOCK OPTION AGREEMENT


         This OPTION AGREEMENT is entered into by and between HighwayMaster
Communications, Inc., a Delaware corporation (the "Company"), and Terry Parker,
a member of the Board of Directors of the Company (the "Optionee"), regarding
stock of the Company.

                                    RECITALS:

         A.    The Board of Directors of the Company has voted to offer to 
Optionee a position on the Board of Directors of the Company, and Optionee has
accepted such offer;

         B.    The Board of Directors of the Company wishes to provide Optionee
with certain compensation in connection with his service on the Board of
Directors of the Company;

         NOW, THEREFORE, in consideration of the premises and the benefits to be
derived from the mutual observance of the covenants and promises contained
herein and other good and valuable consideration, the sufficiency of which is
hereby acknowledged, the parties hereto agree as follows:


         1.    Grant of Option. The Company hereby grants to the Optionee 
effective as of the date set forth in Section 3 hereof (the "Date of Grant"),
the right and option (the "Option") to purchase up to the aggregate number of
shares of common stock, par value $.01 per share, of the Company (the "Common
Stock") set forth in Section 3 hereof, subject to adjustment pursuant to Section
4 hereof and subject to the Optionee's acceptance and agreement to the terms,
conditions and restrictions set forth below.

         2.    Exercise Price. Subject to adjustment pursuant to Section 4, the
exercise price payable by the Optionee upon exercise of this Option is set forth
in Section 3 hereof.


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         3.    Specified Information. This Option Agreement shall apply with
respect to the following specific information:

               a.   Date of Grant: April 4, 1995

               b.   Name of Optionee: Terry Parker

               c.   Number of Shares Covered by Option: 1.9477

               d.   Option Exercise Price Per Share: $14,785.71

         4.    Adjustments to Number of Shares and Option Price. The price to be
paid and the number of shares to be issued upon exercise of outstanding Options
shall be subject to adjustment by the Board of Directors of the Company, in its
sole discretion, to reflect any stock split, stock dividend, recapitalization,
merger, consolidation, reorganization, combination or exchange of shares or
similar event.

         5.    Tax Status. This Option shall not be deemed to qualify as an
incentive option under Section 422 of the Internal Revenue Code of 1986.

         6.    Exercise of Option. Except as otherwise provided in this Option
Agreement, Optionee may exercise all or any portion of this Option at any time
and from time to time after the Date of Grant.

         7.    Expiration of Option. This Option shall expire and cease to be
exercisable on the sixth anniversary of the Date of Grant or such earlier date
as may be specified in this Option Agreement. 

         8.    Termination of Affiliation.

               (a)  Subject to the following provisions of this Section 8, this
         Option may not be exercised unless at the time of exercise the
         Optionee is a member of the Board of Directors of the Company or a
         Subsidiary.

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               (b)  If the Optionee's position as a member of the Board of
         Directors of the Company or a Subsidiary shall terminate for any
         reason other than death, the Optionee may exercise this Option, to the
         same extent it was exercisable on the date of such termination, during
         the 60-day period following the date of such termination. In no event
         may the Optionee exercise this Option later than the date on which the
         Option would have expired under Section 7 hereof.

               (c)  If the Optionee's position as a member of the Board of
         Directors of the Company or a Subsidiary shall terminate by reason of
         the Optionee's death, the executor or administrator of the Optionee's
         estate or the person to whom this Option is transferred by will or the
         laws of descent or distribution may exercise this Option with respect
         to any or all shares covered by this Option within 60 days after the
         date of the Optionee's death, but in no event may this Option be
         exercised later than the date on which the Option would have expired
         if the Optionee had lived. Such exercise of the Options shall only be
         permitted to the extent that the Optionee was entitled to exercise the
         Option at the date of his or her death and, to the extent the Option
         is not so exercised, it shall expire at the end of such 60-day period.

         9.    Procedure to Exercise. This Option may be exercised only by 
delivery of a written notice to the Company at its principal office, stating the
number of shares of Common Stock as to which the Option is being exercised and
accompanied by payment in full in cash or by certified check of the exercise
price for all such shares. This Option shall not be deemed exercised in the
event that payment therefor is not received, and shares of Common Stock shall
not be issued upon the exercise of an Option unless the exercise price is paid
in full at the time of exercise.



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         10. Nontransferability of Option. This Option shall not be assignable
or transferable other than by will or the laws of descent and distribution and
shall be exercisable only by the Optionee during his lifetime. No transfer of
this Option Agreement by will or by the laws of descent and distribution shall
be effective to bind the Company unless the Company shall have been furnished
with written notice thereof and a copy of the will and/or such other evidence as
the Committee may determine necessary to establish the validity of the transfer.

         11. Restrictions Regarding Issuance of Stock Pending Registration. If
the listing upon any stock exchange or the registration or qualification under
any federal or state law of any shares of Common Stock to be issued on the
exercise of this Option Agreement should become necessary or desirable, the
Board of Directors of the Company in its sole discretion may determine that
delivery of the certificates for such shares of Common Stock shall not be made
until the listing, registration or qualification shall have been completed. The
Company agrees that it will use its reasonable best efforts to effect any such
listing, registration or qualification; provided, however, that the Company
shall not be required to use its reasonable best efforts to effect such
registration under the Securities Act of 1933 other than on Form S-8 or such
other forms as may be in effect from time to time calling for information
comparable to that presently required to be furnished under Form S-8.

         12. Investment Representation. At such time or times as the Optionee
may exercise this Option, the Optionee shall, upon the request of the Company,
represent in writing (i) that the shares being acquired by the Optionee will not
be sold except pursuant to an effective registration statement, or applicable
exemption from registration, under the Securities Act of 1933, as amended, (ii)
that it is the Optionee's intention to acquire the shares being acquired for
investment only and not with a view to distribution thereof, and (iii) other
customary representations as the Company deems necessary or 



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advisable. No shares will be issued unless and until the Company is satisfied as
to the accuracy of such representations.

         13.   Restrictive Legends.

               (a)  Certificates representing shares of Common Stock delivered
         pursuant to the exercise of this Option Agreement shall bear an
         appropriate legend referring to the terms, conditions, and restrictions
         described in this Option Agreement. Any attempt to dispose of any such
         shares of Common Stock in contravention of the terms, conditions and
         restrictions described in this Option Agreement shall be ineffective,
         null and void, and the Company shall not effect any such transfer on 
         its books.

               (b)  Any shares of Common Stock of the Company received by 
         Optionee (or his heirs, legatees, distributees or representative) as a
         stock dividend on, or as a result of a stock split, combination,
         exchange of shares, reorganization, merger, consolidation or otherwise
         with respect to, shares of Common Stock received pursuant to the
         exercise of this Option Agreement, shall be subject to the terms and
         conditions of this Option Agreement and bear the same legend as the
         shares received pursuant to the exercise of this Option Agreement.

         14.   Continued Board Membership. Nothing herein shall confer upon the
Optionee any right to continued membership on the Board of Directors of the
Company or a Subsidiary or shall prevent the Company or Subsidiary which retains
the Optionee from terminating such relationship at any time, with or without
cause.

         15.   Rights as Shareholder. Nothing herein is intended to or shall 
give to the Optionee any right or status of any kind as a stockholder of the
Company in respect of any shares of Common Stock covered by this Option or
entitle the Optionee to any dividends or distributions thereon unless and until
a share certificate representing such shares shall have been delivered to the
Optionee and 



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registered in the Optionee's name. Upon the issuance and receipt of such
certificate or certificates, the Optionee shall have absolute ownership of the
shares of Common Stock evidenced thereby, including the right to vote such
shares, to the same extent as any other owner of shares of Common Stock, and to
receive dividends thereon, subject, however, to the terms, conditions and
restrictions of this Option Agreement.

         16.   Merger or Reorganization of the Company. If the Company shall at
any time participate in a reorganization and (A) the Company is not the
surviving entity, or (B) the Company is the surviving entity and the holders of
Common Stock are required to exchange their shares for property and/or
securities, the Company shall give Optionee written notice of such fact on or
before 15 days before such merger or consolidation, and this Option Agreement
shall be exercisable in full after receipt of such notice and prior to such
merger or consolidation. Options not exercised prior to such merger or
consolidation shall expire on the occurrence of such merger or consolidation. A
sale of all or substantially all the assets of the Company for consideration
(apart from the assumption of obligations) consisting primarily of securities
shall be deemed a merger or consolidation for the foregoing purposes.

         17.   Dissolution or Liquidation of the Company. In the event of the
proposed dissolution or liquidation of the Company, the Options granted
hereunder shall terminate as of a date to be fixed by the Board of Directors of
the Company, provided that not less than 15 days' prior written notice of the
date so fixed shall be given to Optionee, and the Optionee shall have the right,
during the 15-day period preceding such termination, to exercise his Option.

         18.   Interpretation. If and when questions arise from time to time as
to the intent, meaning or application of the provisions of this Option
Agreement, such questions shall be decided by the Board of Directors of the
Company in its sole discretion, and any such decision shall be conclusive 



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and binding on the Optionee. The Optionee hereby agrees that this Option is
granted and accepted subject to such condition and understanding.

         19.   Withholding of Taxes. Upon exercise of this Option (either wholly
or in part), the Optionee must pay to the Company, or make arrangements
satisfactory to the Company regarding payment of, any federal, state or local
taxes of any kind which may be required to be withheld in connection with the
issuance to the Optionee of Common Stock upon exercise of this Option.

         20.   Notices. All notices and other communications hereunder shall be 
in writing and shall be deemed to have been duly given if delivered personally,
mailed certified mail (return receipt requested) or sent by overnight delivery
service, cable, telegram, facsimile transmission or telex to the Optionee or the
Company at the address set forth below or at such other addresses as shall be
specified by the parties by like notice:

                        HighwayMaster Communications, Inc.
                        16479 Dallas Parkway
                        Suite 710
                        Dallas, Texas 75248
                        Fax:  (214) 250-0182
                        Attn:  William C. Kennedy, Jr.

                        Terry Parker
                        1730 BRIERCROFT COURT
                        CARROLLTON, TX 75006   

         21.   Confidentiality. Unless otherwise permitted by the Chairman of 
the Board or the President of the Company, Optionee agrees to keep confidential
the terms of this Option Agreement.

         IN WITNESS WHEREOF, the undersigned have executed this Option Agreement
to be effective as of the Date of Grant set forth above.

                                       HIGHWAYMASTER COMMUNICATIONS, INC.


                                       By: /s/ WILLIAM C. KENNEDY, JR.
                                          -------------------------------------
                                       Name:   William C. Kennedy, Jr.
                                            -----------------------------------
                                       Title:  Chairman
                                             ----------------------------------



                                         /s/ TERRY PARKER
                                       ----------------------------------------
                                       Terry Parker, Optionee


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