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                     SECURITIES AND EXCHANGE COMMISSION

                           Washington, D.C.  20549

                                SCHEDULE 13G

                  Under the Securities Exchange Act of 1934

                              (Amendment No.  )

NAME OF ISSUER:                 Trimble Navigation LTD.

TITLE OF CLASS OF SECURITIES:   Common Stock 

CUSIP NUMBER:                   896239-100 

CUSIP NO.                       896239-100 

(1)     Names of Reporting Persons                      MELLON BANK CORPORATION
        SS or IRS Identification Nos. Of Above Person   IRS No. 25-1233834

(2)     Check the Appropriate Box if a Member of a Group (See Instructions) 
                                                        (a)  (   )   (b)  (   )

(3)     SEC Use Only

(4)     Citizenship or Place of Organization            United States

Number of Shares          (5)     Sole Voting Power             1,261,695
Beneficially            
Owned by Each             (6)     Shared Voting Power                   0
Reporting Person
With                      (7)     Sole Dispositive Power        1,339,700 

                          (8)     Shared Dispositive Power         12,800

(9)     Aggregate Amount Beneficially Owned by Each Reporting Person
                                                                1,357,623 

(10)    Check if the Aggregate Amount in Row (9) Excludes Certain
        Shares (See Instructions)                                  (   )

(11)    Percent of Class Represented by Amount in Row (9) 6.01         

(12)    Type of Reporting Person (See Instructions)                   HC

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                      SECURITIES AND EXCHANGE COMMISSION
                           Washington, D.C.  20549
                                      
                                 SCHEDULE 13G
               (Under the Securities and Exchange Act of 1934)

Item 1(a)   Name of Issuer: Trimble Navigation LTD.

Item 1(b)   Address of Issuer's Principal Executive Offices:
            645 N. MARY AVE., SUNNYVALE, CA 94088
                                                        

Item 2(a)   Name of Person Filing:   Mellon Bank Corporation and any other 
                                     reporting person(s) identified on the 
                                     second part of the cover page(s).

Item 2(b)   Address of Principal Business Office, or if None, Residence: 
                                                 c/o Mellon Bank Corporation
                                                 One Mellon Bank Center
                                                 Pittsburgh, Pennsylvania 15258
                                                 (for all reporting persons)

Item 2(c)   Citizenship:                          United States

Item 2(d)   Title of Class of Securities:         Common Stock

Item 2(e)   CUSIP Number: 896239-100                         

Item 3      See Item 12 of cover page(s) ("Type of Reporting
            Person") for each reporting person.

                BK =  Bank as defined in Section 3(a)(6) of the Act

                IV =  Investment Company registered under Section 8 of the
                      Investment Company Act

                IA =  Investment Adviser registered under Section 203 of the
                      Investment Advisers Act of 1940

                EP =  Employee Benefit Plan, Pension Fund which is subject to
                      the provisions of the Employee Retirement Income 
                      Security Act of 1974 or Endowment Fund; see 
                      Section 240.13-d(1)(b)(1)(ii)(F)

                HC =  Parent Holding Company, in accordance with Section
                      240.13-d(1)(b)(1)(ii)(G)

Item 4   Ownership:   See Items 5 through 9 and 11 of cover page(s)
                      as to each reporting person.

The amount beneficially owned includes, where appropriate, securities
not outstanding which are subject to options, warrants, rights or
conversion privileges that are exercisable within 60 days.  The filing
of this Schedule 13G shall not be construed as an admission that
Mellon Bank Corporation, or its direct or indirect subsidiaries,
including Mellon Bank, N.A., are for the purposes of Section 13(d) or
13(g) of the Act, the beneficial owners of any securities covered by
this Schedule 13G.

The following information applies if checked:   (   )   Mellon Bank, N.A. is the
trustee of the issuer's employee benefit plan (the "Plan"), which is subject to
ERISA.  The securities reported include all shares held of record by Mellon
Bank, N.A. as trustee of the Plan which have not been allocated to the
individual accounts of employee participants in the Plan. The reporting person,
however, disclaims beneficial ownership of all shares that have been allocated
to the individual accounts of employee participants in the Plan for which
directions have been received and followed.

Item 5   Ownership of Five Percent or Less of a Class:   If this
statement is being filed to report the fact that as of the date hereof
the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following  (   )

Item 6   Ownership of More than Five Percent on Behalf of Another
Person:   All of the securities are beneficially owned by Mellon Bank
Corporation and direct or indirect subsidiaries in their various
fiduciary capacities.  As a result, another entity in every instance
is entitled to dividends or proceeds of sale.  The number of
individual accounts holding an interest of 5% or more is ( 0 ).



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Item 7   Identification and Classification of the Subsidiary Which Acquired 
the Security Being Reported by the Parent Holding Company:    See Exhibit I.

Item 8   Identification and Classification of Members of the Group:     N/A

Item 9   Notice of Dissolution of Group:                                N/A

Item 10   Certification:   By signing below I certify that, to the
best of my knowledge and belief, the securities referred to above were
acquired in the ordinary course of business and were not acquired for
the purpose of and do not have the effect of changing or influencing
the control of the issuer of such securities and were not acquired in
connection with or as a participant in any transaction having such
purposes or effect.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement is true,
complete and correct.  This filing is signed by Mellon Bank
Corporation on behalf of all reporting entities pursuant to Rule
13d-1(f)(1) promulgated under the Securities and Exchange Act of 1934,
as amended.

Date: January 23, 1998

MELLON BANK CORPORATION

                                                                            
By:   WILLIAM L. DAWSON, JR.
    ------------------------
      William L. Dawson, Jr.
      Senior Vice President, 
      Mellon Bank, N.A.
      Attorney-In-Fact for 
      Mellon Bank Corporation

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                           EXHIBIT I


The shares reported on the attached Schedule 13G are beneficially owned by the
following direct or indirect subsidiaries of Mellon Bank Corporation, as 
marked (X):


(A) The Item 3 classification of each of the subsidiaries listed below is 
"Item 3(b) Bank as defined in Section 3(a)(6) of the Act."

        ( X )   Boston Safe Deposit and Trust Company
        (   )   Mellon Trust of California
        (   )   Mellon Trust of New York
        ( X )   Mellon Bank, N.A. (also parent holding company of the Dreyfus
                Corporation and Mellon Equity Associates)
        (   )   Mellon Bank (Delaware) National Association
        (   )   Mellon Bank (MD)
        (   )   Mellon Trust Florida
        (   )   Mellon, F.S.B.

(B) The Item 3 classification of each of the subsidiaries listed below is 
"Item 3(e) Investment Advisor registered under Section 203 of the Investment 
Advisers Act of 1940."

        (   )   Franklin Portfolio Associates Trust
        (   )   Laurel Capital Advisors
        ( X )   Mellon Capital Management Corporation
        (   )   Mellon Equity Associates
        (   )   Boston Safe Advisors
        ( X )   The Boston Company Asset Management, Inc.
        ( X )   The Dreyfus Corporation (also parent holding company of
                Dreyfus Investment Advisors, Inc.)
        (   )   Dreyfus Investment Advisors, Inc.

(C) The Item 3 classification of each of the legal entities listed below is
"Item 3(g) Parent Holdings Company, in accordance with Section
240.13d-I(b)(ii)(G).

        ( X )   Mellon Bank Corporation
        ( X )   Boston Group Holdings, Inc. (parent holding company of The
                Boston Company, Inc.)
        ( X )   The Boston Company, Inc. (parent holding company of Boston Safe
                Advisors, Inc., The Boston Company Asset Management, Inc.,
                Boston Safe Deposit and Trust Company, Mellon Trust of 
                California, Mellon Trust of New York and Mellon Trust Florida)
        ( X )   MBC Investment Corporation (parent holding company of Laurel
                Capital Advisors, Franklin Portfolio Associates, Mellon Bank,
                F.S.B. and Mellon Capital Management Corporation)
        (   )   Mellon Financial Corporation (MD)(parent holding company of
                Mellon Bank (MD)

NOTE: All of the legal entities listed under (A) and (B) above are direct or
indirect subsidiaries of Mellon Bank Corporation. Beneficial ownership of more
than five percent of the class by any one of the subsidiaries or intermediate
parent holding companies listed above is reported on a joint reporting person
page for that subsidiary on the attached Schedule 13G and is incorporated in
the total percent of class reported on Mellon Bank Corporation's reporting
person page. (Do not add the shares or percent of class reported on each joint
reporting person page on the attached Schedule 13G to determine the total
percent of class for Mellon Bank Corporation.)