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                                                                       EXHIBIT 4

                               FOURTH AMENDMENT TO
                           CREDIT AGREEMENT AND WAIVER


                                      Among


                         ALLEGHENY TELEDYNE INCORPORATED
                                 as the Borrower


                    THE FINANCIAL INSTITUTIONS PARTY THERETO
                                 as the Lenders


         BANK OF AMERICA, N.A. (FORMERLY BANK OF AMERICA NATIONAL TRUST
                            AND SAVINGS ASSOCIATION)
                            THE CHASE MANHATTAN BANK
                                MELLON BANK, N.A.
                                       and
                         PNC BANK, NATIONAL ASSOCIATION
                               as Managing Agents


                                       and


                         PNC BANK, NATIONAL ASSOCIATION
                  as the Documentation and Administrative Agent



                                   Dated as of

                                 August 6, 1999


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                 FOURTH AMENDMENT TO CREDIT AGREEMENT AND WAIVER


         THIS FOURTH AMENDMENT TO CREDIT AGREEMENT AND WAIVER (the "Fourth
Amendment") made as of August 6, 1999, to that certain Credit Agreement dated as
of August 30, 1996 as amended by the First Amendment to Credit Agreement dated
as of August 31, 1997, the Second Amendment to Credit Agreement dated as of
March 24, 1998, and the Third Amendment to Credit Agreement dated as of March
30, 1999 (the Credit Agreement together with the exhibits and schedules thereto
and all modifications, amendments, extensions, renewals, substitutions or
replacements prior to the date hereof, the "Existing Agreement"), among
ALLEGHENY TELEDYNE INCORPORATED as the Borrower (the "Borrower"), the FINANCIAL
INSTITUTIONS listed on the signature pages hereto and each other financial
institution which from time to time becomes a party hereto in accordance with
Section 9.6a (individually a "Lender" and collectively the "Lenders"), BANK OF
AMERICA, N.A. (formerly Bank of America National Trust and Savings Association),
THE CHASE MANHATTAN BANK, MELLON BANK, N.A. and PNC BANK, NATIONAL ASSOCIATION
as Managing Agents (individually a "Managing Agent" and collectively the
"Managing Agents") and PNC BANK, NATIONAL ASSOCIATION, a national banking
association, Documentation and Administrative Agent for the Lenders (in such
capacity the "Agent").

                                   WITNESSETH:

         WHEREAS, the Borrower and the initial Lenders, the Managing Agents and
the Agent entered into the Existing Agreement pursuant to which the Lenders made
certain financial accommodations available to the Borrower including a Revolving
Credit Commitment;

         WHEREAS, the Borrower and the Lenders, the Managing Agents and the
Agent desire to amend the Existing Agreement as set forth herein.

         NOW THEREFORE, in consideration of the mutual premises contained herein
and other good and valuable consideration, the Borrower and the Lenders with the
intent to be legally bound hereby, agree that the Existing Agreement shall be
amended as follows:

                                    ARTICLE I

                        AMENDMENTS TO EXISTING AGREEMENT

         SECTION 1.01. ADDITIONAL DEFINITIONS. Section 1.1 of the Existing
Agreement is hereby amended such that the following definition shall be added
thereto in the appropriate alphabetical order:

         "Aerospace and Electronics Assets" means the assets of Subsidiaries of
TI which are directly related to TI's aerospace and electronics line of
business.

         "Aerospace Credit Agreement" shall have the meaning ascribed to it in
Article II of the Fourth Amendment.

         "Aerospace Subsidiary" means a corporation to be formed by Teledyne
Industries on or before the Reorganization Date to which shall be contributed
the Aerospace and Electronics Assets.



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         "Consumer Products Assets" means the assets of Subsidiaries of TI which
are directly related to TI's consumer products line of business.

         "Consumer Products Credit Agreement" shall have the meaning ascribed to
it in Article II of the Fourth Amendment.

         "Consumer Products Subsidiary" means a corporation to be formed by
Teledyne Industries on or before the Reorganization Date to which shall be
contributed the Consumer Products Assets.

         "Fourth Amendment" means the Fourth Amendment to Credit Agreement and
Waiver among the Borrower, the Lenders, the Managing Agents and the Agent dated
as of August 6, 1999.

         "Fourth Amendment Effective Date" shall mean August 6, 1999.

         "Newco LLC" means the Delaware limited liability company to be formed
by the Borrower and having as its sole member the Borrower.

         "Reorganization Date" means the date on which the Spin-off occurs.

         "Spin-off" means the series of transactions in which (i) Teledyne
Industries will create two wholly-owned Subsidiaries: (A) Aerospace Subsidiary
which ultimately shall own, directly or indirectly, the Aerospace and
Electronics Assets and (B) Consumer Products Subsidiary which ultimately shall
own, directly or indirectly, the Consumer Products Assets, (ii) the Borrower
will contribute TI to Newco LLC, (iii) TI will be dissolved into Newco LLC, (iv)
Newco LLC or Teledyne Industries (A) shall contribute the Aerospace and
Electronics Assets to Aerospace Subsidiary and (B) shall contribute the Consumer
Products Assets to Consumer Products Subsidiary, and (v) the shares of Aerospace
Subsidiary and Consumer Products Subsidiary shall be distributed to the existing
stockholders of the Borrower in a tax free reorganization under Section 355 of
the Internal Revenue Code.

         SECTION 1.02. AMENDMENT TO SECTION 4.11. Section 4.11 of the Existing
Agreement is amended and restated in its entirety to read as follows:

                  On and after the Fourth Amendment Effective Date (i) the
                  Borrower (x) shall be the legal and beneficial owner of and
                  shall retain all voting rights relating to all of the issued
                  and outstanding capital stock of ATI Funding and (y) shall be
                  the legal and beneficial owner of and shall retain all voting
                  rights relating to all of the issued and outstanding capital
                  stock of TI prior to the contribution of the capital stock of
                  TI to Newco LLC described below, and (ii) ATI Funding shall be
                  the legal and beneficial owner of and shall retain all voting
                  rights relating to all of the issued and outstanding capital
                  stock of each of ALC and OREMET. After the Fourth Amendment
                  Effective Date and on or prior to the Reorganization Date, (i)
                  the Borrower shall contribute the outstanding capital stock of
                  TI to Newco LLC, which shall be a wholly owned limited
                  liability company of the Borrower, and (ii) TI shall be
                  dissolved into Newco LLC and the stock of Aerospace Subsidiary
                  and Consumer Products Subsidiary shall be distributed to the
                  stockholders of the Borrower, as a result of which the
                  Borrower shall be the legal and beneficial owner of and shall
                  retain all voting rights relating to all of the issued and




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                  outstanding limited liability interests in Newco LLC and Newco
                  LLC shall be the legal and beneficial owner of all of the
                  issued and outstanding capital stock of Teledyne Industries
                  and thereafter during the term hereof shall retain all voting
                  rights relating to all of the issued and outstanding capital
                  stock of Teledyne Industries.

         SECTION 1.03. NO OTHER AMENDMENTS. The amendments to the Existing
Agreement set forth in Sections 1.01 and 1.02 inclusive above do not either
implicitly or explicitly alter or amend, except as expressly provided in this
Fourth Amendment, the provisions of the Existing Agreement. The amendments set
forth in Sections 1.01 and 1.02 hereof do not waive, now or in the future,
compliance with any other covenant, term or condition to be performed or
complied with nor do they impair any rights or remedies of the Lenders or the
Agent under the Existing Agreement with respect to any such violation. Nothing
in this Fourth Amendment shall be deemed or construed to be a release of, or a
limitation upon, the Lenders' or the Agents' exercise of any of their respective
rights and remedies under the Existing Agreement and the other Loan Documents,
whether arising as a consequence of any Events of Default which may now exist or
otherwise, and all such rights and remedies are hereby expressly reserved.

                                   ARTICLE II

                                     WAIVER

         SECTION 2.01. In order to allow the Spin-off to occur, the Lenders
hereby waive certain provisions of Section 5.1 of the Existing Agreement to
allow the following:

                  (a) Incurrence of Indebtedness (Aerospace). The Borrower may
         enter into a credit agreement with a group of lenders (the "Aerospace
         Credit Agreement"), the terms and conditions of which may be more
         restrictive than the terms and conditions of the Agreement, and incur
         Indebtedness under the Aerospace Credit Agreement, provided that:

                           (i) the maximum amount of Indebtedness that may be
                  incurred under the Aerospace Credit Agreement shall not exceed
                  $200,000,000.

                           (ii) all of the Borrower's liability under the
                  Aerospace Credit Agreement shall be fully assumed by Aerospace
                  Subsidiary on the Reorganization Date, and thereafter the
                  Borrower shall have no liability under the Aerospace Credit
                  Agreement; and

                           (iii) if the Spin-off does not occur on or before
                  March 31, 2000, the Borrower shall terminate the Aerospace
                  Credit Agreement and pay all amounts due thereunder.

                  (b) Incurrence of Indebtedness (Consumer Products). The
         Borrower may enter into a credit agreement with a group of lenders (the
         "Consumer Products Credit Agreement"), the terms and conditions of
         which may be more restrictive than the terms and conditions of the
         Agreement, and incur Indebtedness under the Consumer Products Credit
         Agreement, provided that:

                           (i) the maximum amount of Indebtedness that may be
                  incurred under the Consumer Products Credit Agreement shall
                  not exceed $80,000,000;



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                           (ii) all of the Borrower's liability under the
                  Consumer Products Credit Agreement shall be fully assumed by
                  Consumer Products Subsidiary on the Reorganization Date, and
                  thereafter the Borrower shall have no liability under the
                  Consumer Products Credit Agreement; and

                           (iii) if the Spin-off does not occur on or before
                  March 31, 2000, the Borrower shall terminate the Consumer
                  Products Credit Agreement and pay all amounts due thereunder.

                                   ARTICLE III

                     BORROWER'S SUPPLEMENTAL REPRESENTATIONS

         SECTION 3.01 INCORPORATION BY REFERENCE. As an inducement to the
Lenders to enter into this Fourth Amendment, the Borrower hereby repeats herein,
for the benefit of the Lenders, the representations and warranties made by the
Borrower in Sections 3.1 through 3.15, inclusive, of the Existing Agreement, as
amended hereby, except that for purposes hereof such representations and
warranties shall be deemed to extend to and cover this Fourth Amendment.

                                   ARTICLE IV

                              CONDITIONS PRECEDENT

         SECTION 4.01. CONDITIONS PRECEDENT. Each of the following shall be a
condition precedent to the effectiveness of this Fourth Amendment:

         (i) The Lenders shall have received, on or before the Fourth Amendment
Effective Date, duly executed counterpart originals of this Fourth Amendment.

         (ii) The following statements shall be true and correct on the Fourth
Amendment Effective Date:

                  (A) except to the extent modified in writing by the Borrower
heretofore delivered to the Lenders, the representations and warranties made
pursuant to Section 3.01 of this Fourth Amendment and in the other Loan
Documents are true and correct on and as of the Fourth Amendment Effective Date
as though made on and as of such date in all material respects;

                  (B) no Event of Default or event which with the giving of
notice or passage of time or both would become an Event of Default has occurred
and is continuing, or would result from the execution of or performance under
this Fourth Amendment;

                  (C) the Borrower has in all material respects performed all
agreements, covenants and conditions required to be performed on or prior to the
date hereof under the Existing Agreement and the other Loan Documents.



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                                    ARTICLE V

                               GENERAL PROVISIONS

         SECTION 5.01. RATIFICATION OF TERMS. Except as expressly amended or
waived by this Fourth Amendment, the Existing Agreement and each and every
representation, warranty, covenant, term and condition contained therein is
specifically ratified and confirmed in all material respects.

         SECTION 5.02. REFERENCES. All notices, communications, agreements,
certificates, documents or other instruments executed and delivered after the
execution and delivery of this Fourth Amendment in connection with the
Agreement, any of the other Loan Documents or the transactions contemplated
thereby may refer to the Existing Agreement without making specific reference to
this Fourth Amendment, but nevertheless all such references shall include this
Fourth Amendment unless the context requires otherwise. From and after the
Fourth Amendment Effective Date, all references in the Existing Agreement and
each of the other Loan Documents to the "Agreement" shall be deemed to be
references to the Existing Agreement as amended hereby.

         SECTION 5.03. COUNTERPARTS. This Fourth Amendment may be executed in
different counterparts, each of which when executed by the Borrower and a Lender
shall be regarded as an original, and all such counterparts shall constitute one
Fourth Amendment.

         SECTION 5.05. CAPITALIZED TERMS. Except for proper nouns and as
otherwise defined herein, capitalized terms used herein as defined terms shall
have the meanings ascribed to them in the Existing Agreement, as amended hereby.

         SECTION 5.05. GOVERNING LAW. THIS FOURTH AMENDMENT AND THE RIGHTS AND
OBLIGATIONS HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE
LAWS OF THE COMMONWEALTH OF PENNSYLVANIA WITHOUT REGARD TO THE PROVISIONS
THEREOF REGARDING CONFLICTS OF LAW.

         SECTION 5.06. HEADINGS. The headings of the sections in this Fourth
Amendment are for purposes of reference only and shall not be deemed to be a
part hereof.

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         IN WITNESS WHEREOF, the parties hereto, intending to be legally bound
hereby, have caused this Fourth Amendment to be duly executed by their proper
and duly authorized officers the day first above written.


                                             
PNC BANK, NATIONAL ASSOCIATION, as              ALLEGHENY TELEDYNE INCORPORATED
Lender, Managing Agent and Agent


By:    /s/ DAVID B. GOOKIN           (SEAL)     By:    /s/ R. S. PARK                  (SEAL)
       ------------------------------                  --------------------------------
Name:  David B. Gookin                          Name:  R. S. Park
       ------------------------------------            --------------------------------------
Title: Vice President                           Title: Vice President, Treasurer
       ------------------------------------            --------------------------------------

THE CHASE MANHATTAN BANK, as Lender             BANK OF AMERICA, N.A. (formerly Bank of
and Managing Agent                              America National Trust and Savings
                                                Association), as Lender and Managing Agent
                                                and as successor in interest to NationsBank,
                                                N.A.

By:    /s/ JAMES H. RAMAGE           (SEAL)     By:    /s/ GRETCHEN SPOO               (SEAL)
       ------------------------------                  --------------------------------
Name:  James H. Ramage                          Name:  Gretchen Spoo
       ------------------------------------            --------------------------------------
Title: Vice President                           Title: Vice President
       ------------------------------------            --------------------------------------


THE BANK OF NEW YORK                            MELLON BANK, N.A., as Lender and
                                                Managing Agent

By:    /s/ DOUGLAS OBER              (SEAL)     By:     /s/ ROBERT J. RUCHENBACH       (SEAL)
       ------------------------------                  --------------------------------
Name:  Douglas Ober                             Name:   Robert J. Ruchenbach
       ------------------------------------            --------------------------------------
Title: Senior Vice President                    Title: Assistant Vice President
       ------------------------------------            --------------------------------------


BANK OF TOKYO-MITSUBISHI TRUST                  MORGAN GUARANTY TRUST COMPANY
COMPANY                                         OF NEW YORK

By:                                  (SEAL)     By:    /s/ ROBERT BOTTAMEDI            (SEAL)
       ------------------------------                  --------------------------------
Name:                                           Name:  Robert Bottamedi
       ------------------------------------            --------------------------------------
Title:                                          Title: Vice President
       ------------------------------------            --------------------------------------


THE FIRST NATIONAL BANK OF CHICAGO              THE TORONTO-DOMINION BANK

By     /s/ GARY C. WILSON            (SEAL)     By:                                    (SEAL)
       ------------------------------                  --------------------------------
Name:  Gary C. Wilson                           Name:
       ------------------------------------            --------------------------------------
Title: First Vice President                     Title:
       ------------------------------------            --------------------------------------


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                        [CONTINUATION OF SIGNATURE PAGE]


                                             
THE FUJI BANK LIMITED, NEW YORK                 FIRST UNION NATIONAL BANK, successor
BRANCH                                          by merger to CoreStates Bank, NA

By     /s/ RAYMOND VENTURA           (SEAL)     By:    /s/ DONNA J. EMHART             (SEAL)
       ------------------------------                  --------------------------------
Name:  Raymond Ventura                          Name:   Donna J. Emhart
       ------------------------------------            --------------------------------------
Title: Vice President and Manager               Title: Vice President
       ------------------------------------            --------------------------------------


UNION BANK OF SWITZERLAND, NEW YORK BRANCH      NATIONAL CITY BANK OF PENNSYLVANIA

By                                   (SEAL)     By:    /s/ MICHAEL A. HEINRICHER       (SEAL)
       ------------------------------                  --------------------------------
Name:                                           Name:   Michael A. Heinricher
       ------------------------------------            --------------------------------------
Title:                                          Title: Assistant Vice President
       ------------------------------------            --------------------------------------







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