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                                                                  EXHIBIT 4.2(a)


                                                                  CONFORMED COPY


                   AMENDMENT NO. 1 TO 364-DAY CREDIT AGREEMENT


         AMENDMENT dated as of July 21, 1999 among LITTON INDUSTRIES, INC. (the
"BORROWER"), the BANKS listed on the signature pages hereof (the "BANKS"), and
MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Administrative Agent (the
"ADMINISTRATIVE AGENT").



                              W I T N E S S E T H :

         WHEREAS, the parties hereto have heretofore entered into the 364-Day
Credit Agreement dated as of March 24, 1999 (the "AGREEMENT") and desire to
amend the Agreement as set forth herein;

         NOW, THEREFORE, the parties hereto agree as follows:

         SECTION 1. Definitions; References. Unless otherwise specifically
defined herein, each term used herein which is defined in the Agreement shall
have the meaning assigned to such term in the Agreement. Each reference to
"hereof", "hereunder", "herein" and "hereby" and each other similar reference
and each reference to "this Agreement" and each other similar reference
contained in the Agreement shall after this Amendment becomes effective, refer
to the Agreement as amended hereby.

         SECTION 2. Definition of Consolidated EBIT. The definition of
"Consolidated EBIT" in Section 1.01 is amended to read as follows:

                  "CONSOLIDATED EBIT" means, for any period, the sum of
Consolidated Net Income for such period plus, to the extent deducted in the
determination of such Consolidated Net Income, Consolidated Interest Expense for
such period and the provision for income taxes for such period; provided that
Consolidated EBIT shall be adjusted to exclude the effect of up to $110,000,000
in non-recurring charges relating to divestiture/exit of non-core businesses and
plant consolidation subsequent to July 31, 1998.

         SECTION 3. Definition of Consolidated EBITDA. The definition of
"Consolidated EBITDA" in Section 1.01 is amended to read as follows:


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                  "CONSOLIDATED EBITDA" means, for any period, the Consolidated
Net Income of the Borrower and its Consolidated Subsidiaries for such period
before cumulative effect of accounting changes, provision for income tax,
interest expense and depreciation and amortization expense; provided that
Consolidated EBITDA shall be adjusted to exclude the effect of up to
$110,000,000 in non-recurring charges relating to divestiture/exit of non-core
businesses and plant consolidation subsequent to July 31, 1998.

         SECTION 4.  Leverage Ratio.  Section 5.05 is amended to read as
follows:

                           SECTION 5.05.  Leverage Ratio. The Leverage Ratio
                  will at no time exceed 320%.

         SECTION 5.  Representations and Warranties.  The Borrower hereby
represents and warrants that as of the date hereof and after giving effect
hereto:

         (a)   no Default under the Agreement has occurred and is continuing;
and

         (b) each representation and warranty of the Borrower set forth in the
Agreement is true and correct as though made on and as of this date.

         SECTION 6.  Governing Law.  This Amendment shall be governed by and
construed in accordance with the laws of the State of New York.

         SECTION 7. Counterparts; Effectiveness. This Amendment may be signed in
any number of counterparts, each of which shall be an original, with the same
effect as if the signatures thereto and hereto were upon the same instrument.
This Amendment shall become effective as of the date hereof when the Agent shall
have received duly executed counterparts hereof signed by the Borrower and the
Required Banks (or, in the case of any party as to which an executed counterpart
shall not have been received, the Agent shall have received telegraphic, telex
or other written confirmation from such party of execution of a counterpart
hereof by such party).


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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of the date first above written.

                                         LITTON INDUSTRIES, INC.

                                         By: /s/ Timothy G. Paulson
                                             -----------------------------------
                                             Name: Timothy G. Paulson
                                             Title: Vice President and Treasurer


                                         MORGAN GUARANTY TRUST
                                           COMPANY OF NEW YORK, as Bank
                                           and Administrative Agent

                                         By: /s/ Sovonna L. Day
                                             -----------------------------------
                                             Name: Sovonna L. Day
                                             Title: Vice President

                                         By: /s/ Robert Bottamedi
                                             -----------------------------------
                                             Name: Robert Bottamedi
                                             Title: Vice President


                                         BANK OF AMERICA, N.A.

                                         By: /s/ Brad W. DeSpain
                                             -----------------------------------
                                             Name: Brad W. DeSpain
                                             Title: Managing Director


                                         THE CHASE MANHATTAN BANK

                                         By: /s/ Richard C. Smith
                                             -----------------------------------
                                             Name: Richard C. Smith
                                             Title: Vice President


                                         THE BANK OF NEW YORK

                                         By: /s/ Mehrasa Raygani
                                             -----------------------------------
                                             Name: Mehrasa Raygani
                                             Title: Assistant Vice President

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                                         THE BANK OF NOVA SCOTIA

                                         By: /s/ R. P. Reynolds
                                             -----------------------------------
                                             Name: R. P. Reynolds
                                             Title: Relationship Manager


                                         BANQUE NATIONALE DE PARIS

                                         By: /s/ C. Bettles
                                             -----------------------------------
                                             Name: C. Bettles
                                             Title: Sr. V.P. & Manager

                                         By: /s/ Brian Dixon
                                             -----------------------------------
                                             Name: Brian Dixon
                                             Title: V.P.


                                         CREDIT SUISSE FIRST BOSTON

                                         By: /s/ Thomas G. Muoio
                                             -----------------------------------
                                             Name: Thomas G. Muoio
                                             Title: Vice President

                                         By: /s/ Jennifer E. Toth
                                             -----------------------------------
                                             Name: Jennifer E. Toth
                                             Title: Analyst


                                         THE FIRST NATIONAL BANK OF
                                           CHICAGO

                                         By: /s/ Betty Francis-Similton
                                             -----------------------------------
                                             Name: Betty Francis-Similton
                                             Title: Customer Service Officer

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                                         WELLS FARGO BANK, N.A.

                                         By: /s/ Catherine M. Wallace
                                             -----------------------------------
                                             Name: Catherine M. Wallace
                                             Title: Vice President

                                         By: /s/ Felynn C. Quilo
                                             -----------------------------------
                                             Name: Felynn C. Quilo
                                             Title: Assistant Vice President


                                         CITICORP USA, INC.

                                         By: /s/ Hillary Savoie
                                             -----------------------------------
                                             Name: Hillary Savoie
                                             Title: Attorney-in-Fact


                                         BANCO DI ROMA - SAN FRANCISCO BRANCH

                                         By:
                                             -----------------------------------
                                             Name:
                                             Title:

                                         By:
                                             -----------------------------------
                                             Name:
                                             Title:


                                         UNICREDITO ITALIANO

                                         By: /s/ Nicola Longo Dente
                                             -----------------------------------
                                             Name: Nicola Lango Dente
                                             Title: First Vice President

                                         By: /s/ Saiyed A. Abbas
                                             -----------------------------------
                                             Name: Saiyed A. Abbas
                                             Title: Vice President

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                                         MELLON BANK, N.A.

                                         By: /s/ J. Cate
                                             -----------------------------------
                                             Name: J. Cate
                                             Title: Vice President


                                         THE NORTHERN TRUST COMPANY

                                         By: /s/ Nicole Boehm
                                             -----------------------------------
                                             Name:  Nicole Boehm
                                             Title: Officer