1
                                                                    EXHIBIT 3.13

                            CERTIFICATE OF AMENDMENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                            TENNECO AUTOMOTIVE INC.


     Tenneco Automotive Inc., a corporation duly organized and existing under
the General Corporation Law of the State of Delaware (the "Corporation"), does
hereby certify that:

     1. The Certificate of Incorporation of the Corporation is hereby amended
by deleting Paragraph 1 thereof and inserting the following in lieu thereof:

          "1. The name of the corporation is Tenneco Automotive Operating
          Company Inc."

     2. The foregoing amendment was duly adopted in accordance with the
provisions of Sections 242 and 228 (by the written consent of the sole
stockholder of the Corporation) of the General Corporation Law of the State of
Delaware.




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     IN WITNESS WHEREOF, Tenneco Automotive Inc. has caused this Certificate to
be executed by its duly authorized officer, on this 5th day of November, 1999.

                                              TENNECO AUTOMOTIVE INC.


                                              By: /s/ MARK P. FRISSORA
                                                  -----------------------------
                                                  Mark P. Frissora, President






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                           CERTIFICATE OF DESIGNATION
                            PREFERENCES AND RIGHTS OF
                               7% PREFERRED STOCK

                             TENNECO AUTOMOTIVE INC.

      Pursuant to Section 151 of the General Corporation Law of the State of
Delaware

      The undersigned, Vice President and Secretary of Tenneco Automotive Inc.,
a corporation organized and existing under the General Corporation Law of the
State of Delaware (the "Corporation"), in accordance with the provisions of
Section 103 thereof, DO HEREBY CERTIFY:

      That pursuant to the authority conferred upon the Board of Directors by
the Certificate of Incorporation of the said Corporation, the said Board of
Directors on October 31, 1997, adopted the following resolution creating a
series of 500,000 shares of Preferred Stock designated as 7% Preferred Stock;

            RESOLVED, that pursuant to the authority vested in the Board of
      Directors of this Corporation in accordance with the provisions of its
      Certificate of Incorporation, a series of Preferred Stock of the
      Corporation be and it hereby is created, and that the designation and
      amount thereof and the voting powers, preferences and relative,
      participating, optional and other special rights of the shares of such
      series, and the qualifications, limitations or restrictions thereof are as
      follows:

            Section 1. Designation and Amount. The shares of such series shall
      be designated as "7% Preferred Stock" and the number of shares
      constituting such series shall be 500,000.

            Section 2. Dividends and Distributions.

            (A) The dividend rate on the shares of Preferred Stock shall be
      $7.00, per annum, payable by the Corporation on the 31" day of January
      commencing




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      in the year 1998 (each annual dividend payment is hereinafter referred to
      as an "Annual Payment Date") so long as any shares of the 7% Preferred
      Stock are outstanding, in cash in United States dollars to each holder of
      record of such shares.

            (B) The holder of record of any share of 7% Preferred stock entitled
      to receive a dividend payment pursuant to Section 2(a) above shall be the
      holder of record of such shares as of the close of business on the first
      day of January in the year such dividend payment is to be made, as shown
      on the stockholder records of the Corporation.

            (C) Dividends shall begin to accrue and be cumulative on outstanding
      shares of 7% Preferred Stock from the date of issue of such shares and the
      first annual dividend shall be adjusted pro rata from the date of issuance
      to the first annual payment date on the basis of a 360-day year. Accrued
      but unpaid dividends shall not bear interest. Dividends paid on the shares
      of 7% Preferred Stock in an amount less than the total amount of such
      dividends at the time accrued and payable on such shares shall be
      allocated pro rata on a share-by-share basis among all such shares at the
      time outstanding. Accrued and unpaid dividends shall be prorated to the
      date of redemption on the basis of a 360-day year.

            Section 3. Voting Rights. The holders of the shares of 7% Preferred
      Stock shall not be entitled or permitted to vote on any matter required or
      permitted to be voted upon by the stockholders of the Corporation, except
      as may be otherwise required by Delaware law.

            Section 4. Reacquired Shares. Any shares of 7% Preferred Stock
      purchased or otherwise acquired by the corporation in any manner
      whatsoever shall be retired and canceled promptly after the acquisition
      thereof. All such shares shall upon their cancellation become authorized
      but unissued shares of Preferred Stock and may be reissued as part of a
      new series of Preferred Stock to be created by resolution or resolutions
      of the Board of Directors, subject to the conditions and restrictions on
      issuance set forth herein.

            Section 5. Liquidation, Dissolution or Winding Up. In the event of
      any voluntary or involuntary liquidation, dissolution or winding up of the
      Corporation, the holders of the 7% Preferred Stock shall be entitled to
      receive the $100.00 per share,



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      plus accrued dividends to the date of distribution, whether or not earned
      or declared.

            Section 6. Optional Redemption. (a) The 7% Preferred Stock shall be
      redeemable, the whole or any part, at any time at the option of the
      Corporation at a redemption price equal to $100 per share, plus, in each
      case, an amount equal to accrued and unpaid accumulated dividends to the
      date of such redemption; provided, however, that the redemption price
      payable upon any redemption occurring prior to November 1, 2017 shall be
      $105 per share, plus, in each case, an amount equal to accrued and unpaid
      accumulated dividends to the date of such redemption. Accrued and unpaid
      dividends shall be prorated to the date of redemption on the basis of a
      360-day year.

            (b) Notice of any such redemption shall be given by mailing to the
      holders of the 7% Preferred Stock a notice of such redemption, first class
      postage prepaid, not later than the thirtieth day and not earlier than the
      sixtieth day before the date fixed for redemption, at their last address
      as the same shall appear upon the books of the Corporation. Any notice
      which is mailed in the manner herein provided shall be conclusively
      presumed to have been duly given, whether or not the shareholder received
      such notice, and failure duly to give such notice by mail, or any defect
      in such notice, to any holder of 7% Preferred Stock shall not affect the
      validity of the proceedings for the redemption of such 7% Preferred Stock.
      If less than all the outstanding shares of 7% Preferred Stock are to be
      redeemed, the redemption shall be made by lot as determined by the Board
      of Directors.




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      IN WITNESS WHEREOF, we have executed and subscribed this Certificate and
do affirm the foregoing as true under the penalties of perjury as of the 31st
day of October, 1997.

                                       TENNECO AUTOMOTIVE INC.


                                       /s/ Karl A. Stewart
                                       -----------------------------------------
                                       Karl A. Stewart
                                       Vice President and Secretary

Attest



/s/ James D. Gaughan
- ---------------------------------
James D. Gaughan
Assistant Secretary





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                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                             TENNECO AUTOMOTIVE INC.

      TENNECO AUTOMOTIVE INC., a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware (the "Company"),
DOES HEREBY CERTIFY:

      FIRST: That pursuant to a written consent of the Board of Directors of the
Company resolutions were adopted setting forth a proposed amendment to the
Certificate of Incorporation of said Company, as amended as of such date (the
"Certificate of Incorporation"), declaring said amendment to be advisable and
directing that the amendment be considered by the sole stockholder of the
Company. The resolution setting forth the proposed amendment is as follows:

      "RESOLVED, that the Board of Directors of the Company hereby approves and
declares it advisable that the Certificate of Incorporation of the Company be
amended (the "Amendment") by deleting Article FOURTH thereof in its entirety and
inserting the paragraph set forth below in lieu thereof:

            "FOURTH: A. The total number of shares of all classes of stock which
      the corporation shall be authorized to issue is 500,200 shares, divided
      into 200 shares of Common Stock, par value $5.00 per share (herein called
      "Common Stock"), and 500,000 shares of Preferred Stock, par value $.01 per
      share (herein called "Preferred Stock").

                   "B.  The Board of Directors of the corporation (the "Board of
            Directors") is hereby expressly authorized, by resolution or
            resolutions thereof, to provide, out of the unissued shares of
            Preferred Stock, for



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            series of Preferred Stock and, with respect to each such series, to
            fix the number of shares constituting such series and the
            designation of such series, the voting powers (if any) of the shares
            of such series, and the preferences and relative, participating,
            optional or other special rights, if any, and any qualifications,
            limitations or restrictions thereof, of the shares of such series.
            The powers, preferences and relative, participating, optional and
            other special rights of each series of Preferred Stock, and the
            qualifications, limitations or restrictions thereof, if any, may
            differ from those of any and all other series at any time
            outstanding.

                   "C.  Except as may otherwise be provided in this Certificate
            of Incorporation (including any certificate filed with the Secretary
            of State of the State of Delaware establishing the terms of a series
            of Preferred Stock in accordance with Section B of this Article
            FOURTH) or by applicable law, each holder of Common Stock, as such,
            shall be entitled to one vote for each share of Common Stock held of
            record by such holder on all matters on which stockholders generally
            are entitled to vote, and no holder of any series of Preferred
            Stock, as such, shall be entitled to any voting powers in respect
            thereof.

                   "D.  Subject to applicable law and the rights, if any, of the
            holders of any outstanding series of Preferred Stock, dividends may
            be declared and paid on the Common Stock at such times and in such
            amounts as the Board of Directors in its discretion shall determine.

                   "E.  Upon the dissolution, liquidation or winding up of the
            corporation, subject to the rights, if any, of the holders of any
            outstanding series of Preferred Stock, the holders of the Common
            Stock shall be entitled to receive the assets of the corporation
            available for distribution to its stockholders ratably in proportion
            to the number of shares held by them.



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                   "F.  The corporation shall be entitled to treat the person in
            whose name any share of its stock is registered as the owner thereof
            for all purposes and shall not be bound to recognize any equitable
            or other claim to, or interest in, such share on the part of any
            other person, whether or not the corporation shall have notice
            thereof, except as expressly provided by applicable law."

      SECOND:  That thereafter, pursuant to the resolution of its Board of
Directors, a unanimous consent of the stockholders of the Company was duly
signed, in accordance with Section 228 of the General Corporation Law of the
State of Delaware (the "DGCL") , as required by the DGCL and the Certificate of
incorporation, adopting the amendment.

      THIRD: That said amendment was duly adopted in accordance with the
provisions of Section 242 of the DGCL.








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      IN WITNESS WHEREOF, said Tenneco Automotive Inc. has caused this
Certificate to be signed as of the 31st day of October, 1997.

                                         TENNECO AUTOMOTIVE INC.



                                         By: /s/ Karl A. Stewart
                                             ---------------------------------
                                             Karl A. Stewart
                                             Vice President and Secretary











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                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                             TENNECO AUTOMOTIVE INC.

      TENNECO AUTOMOTIVE INC., a corporation organized and existing under and
by virtue of the General Corporation Law of the State of Delaware (the
"Company"), DOES HEREBY CERTIFY:

      FIRST: That pursuant to a written consent of the Board of Directors of the
Company resolutions were adopted setting forth a proposed amendment to the
Certificate of incorporation of said Company, as amended as of such date (the
"Certificate of Incorporation"), declaring said amendment to be advisable and
directing that the amendment be considered by the sole stockholder of the
Company. The resolution setting forth the proposed amendment is as follows:

            "RESOLVED, that the Board of Directors of the company hereby
      approves and declares it advisable that the Certificate of Incorporation
      of the Company be amended (the "Amendment") by deleting Paragraph A of
      Article FOURTH thereof in its entirety and inserting the paragraph set
      forth below in lieu thereof:

                   "FOURTH:  A. The total number of shares of all classes of
            Stock which the corporation shall be authorized to issue is 500,250
            shares, divided into 250 shares of Common Stock, par value $5.00 per
            share (herein called "Common Stock") and 500,000 shares of
            Preferred Stock, par value $.01 per share (herein called "Preferred
            Stock").


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            SECOND: That thereafter, pursuant to the resolution of its Board of
Directors, a written consent of the sole stockholder of the Company was duly
signed, in accordance with Section 228 of the General Corporation Law of the
State of Delaware (the "DGCL"), as required by the DGCL and the Certificate of
Incorporation, adopting the amendment.

            THIRD: That said amendment was duly adopted in accordance with the
provisions of Section 242 of the DGCL.

            IN WITNESS WHEREOF, said Tenneco Automotive Inc. has caused this
Certificate to be signed as of the 26th day of January,

                                             TENNECO AUTOMOTIVE INC.

                                             By: /s/ Karl A. Stewart
                                                --------------------------------
                                                 Karl A. Stewart
                                                 Vice President and secretary





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                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                          MONROE AUTO EQUIPMENT COMPANY

            Monroe Auto Equipment Company, a corporation duly organized and
existing under the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify that:

            1.     The Certificate of Incorporation of the Corporation is hereby
amended by deleting Paragraph 1 thereof and inserting the following in lieu
thereof:

                   "1.   The name of the corporation is Tenneco Automotive Inc."

            2.     That the foregoing amendment was duly adopted in accordance
with the provisions of Sections 242 and 228 (by the written consent of the sole
stockholder of the Corporation) of the General Corporation Law of the State of
Delaware.

            IN WITNESS WHEREOF, Monroe Auto Equipment Company has caused this
Certificate to be executed by its duly authorized officer, on this 22nd day of
October, 1996.

                                    MONROE AUTO EQUIPMENT COMPANY

                                    By:   /s/ Robert G. Simpson
                                        ----------------------------------------
                                          Robert G. Simpson
                                          Vice President and Assistant
                                          Secretary







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                       CERTIFICATE OF OWNERSHIP AND MERGER

                                     MERGING

                          MONROE AUTO EQUIPMENT COMPANY

                                      INTO

                                MAEC CORPORATION

                              * * * * * * * * * *

      MAEC CORPORATION (the "Company"), a corporation organized and existing
under the laws of Delaware,

      DOES HEREBY CERTIFY:

      FIRST: That the Company was incorporated on the 13th day of July, 1977,
pursuant to the General Corporation Law of the State of Delaware.

      SECOND: That the Company owns at least ninety percent of the outstanding
shares of the stock of Monroe Auto Equipment Company, a corporation incorporated
on the 30th day of March, 1917, pursuant to the provisions of the laws of the
State of Michigan.

      THIRD: That the Company, by the following resolutions duly adopted by its
Board of Directors by the unanimous written consent of its members on the 22nd
day of July, 1977, determined to and did merge into itself said Monroe Auto
Equipment Company:

            RESOLVED, that the Company merge, and it hereby does merge into
      itself, said Monroe Auto Equipment Company, a Michigan corporation
      ("Monroe") and assumes all of its liabilities and obligations (the
      "Merger"); and it is further

            RESOLVED, that the Merger shall become effective upon the filing of
      an appropriate Certificate of Ownership and Merger with the Secretary of
      State of Delaware; and it is further

            RESOLVED, that the Company change its corporate name by changing
      Paragraph 1 of the Certificate of Incorporation of the Company to read as
      follows: "1. The name of the corporation is Monroe Auto Equipment
      Company."; and it is further

            RESOLVED, that the terms and conditions of the Merger are as
      follows:




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            Tenneco Inc., a Delaware corporation, ("Tenneco") is the owner of
            all of the issued and outstanding shares of capital stock of the
            Company and the Company is the owner of 12,585,029 shares, or
            approximately 97%, of the 12,953,836 issued and outstanding shares
            of Common Stock, par value $1 per share, of Monroe.

            On the effective date of the Merger ("Effective Date") the capital
            stock of each of the Company and Monroe shall be treated as follows:

            (a)    Each share of the then issued and outstanding shares of
                   Common Stock, par value $1 per share, of Monroe ("Monroe
                   Common Stock"), except shares of Monroe Common Stock owned by
                   the Company, shall, by virtue of the Merger and without any
                   action on the part of the holder thereof, be converted into
                   .3846 of a share of Common Stock, par value $5 per share, of
                   Tenneco ("Tenneco Common Stock"), (such shares of Monroe
                   Common Stock to be converted into shares of Tenneco Common
                   Stock are sometimes referred to herein as "Eligible Shares").

            (b)    Each share of Monroe Common Stock then issued and outstanding
                   which is owned by the Company and each of the 76,800 shares
                   of Monroe Common Stock held in the treasury of Monroe shall
                   be cancelled.

            (c)    Each share of capital stock of the Company then issued and
                   outstanding shall be unaffected by the Merger and the
                   certificate(s) representing such shares shall continue to
                   represent the issued and outstanding shares of capital stock
                   of the Company as the Surviving Corporation in the Merger.

            (d)    No scrip or fractional share certificates for Tenneco Common
                   Stock shall be issued, and an outstanding fractional share
                   interest of Tenneco Common Stock shall not entitle the owner
                   thereof to vote, to receive dividends, or to any rights of a
                   stockholder with respect to such fractional interest.
                   Instead, the Exchange Agent (to be appointed by Tenneco and
                   the Company) will act as agent for the holders of Eligible
                   Shares of Monroe Common Stock and shall sell on the New York
                   Stock Exchange, as promptly as possible, but in any event no
                   later than 30 days after the Effective Date, for the accounts
                   of the owners of the fractional share interests, a number of
                   shares of Tenneco Common Stock equal to 141,842


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                   shares, less the number of full shares of Tenneco Common
                   Stock to which the holders of Eligible Shares are entitled.
                   The Exchange Agent will, until July 31, 1980, pay to such
                   owners upon surrender of their Monroe stock certificate(s)
                   the value of such fractional interest (as determined by such
                   sale, net of expenses), without interest. On July 31, 1980,
                   any remaining proceeds of the sale shall be paid over to
                   Tenneco, after which the holders of such certificates
                   remaining outstanding shall look only to Tenneco for payment,
                   subject to the requirements of escheat laws of the various
                   states which may be applicable.

            (e)    All shares of Tenneco Common Stock into which shares of
                   Monroe Common Stock shall have been converted upon the Merger
                   shall be fully paid and nonassessable.

            (f)    No transfer of Eligible Shares of Monroe Common Stock shall
                   be made or consummated after the Effective Date.

      ; and it is further

            RESOLVED, that the form, terms and provisions of the Plan of Merger
      merging Monroe into the Company (proof of July 22, 1977), a copy of which
      is before this Board, be, and the same hereby is, approved, and the
      President or any Vice President, and the Secretary or any Assistant
      Secretary, be, and they hereby are, authorized to execute and deliver said
      Plan of Merger (the "Plan of Merger") substantially in the form approved
      hereby, with such changes therein as the President or Vice President
      executing the same shall approve, his approval to be evidenced
      conclusively by his execution and delivery thereof; and it is further

            RESOLVED, that the Plan of Merger be submitted for adoption by
      Tenneco Inc., the holder of all of the issued and outstanding capital
      stock of the Company; and it is further

            RESOLVED, that, upon adoption of the Plan of Merger by Tenneco Inc.,
      the sole stockholder of the Company, the Secretary or any Assistant
      Secretary of the Company is authorized and directed to certify such fact
      on the Plan of Merger, and the proper officers of the Company are
      authorized and directed to complete the execution, acknowledgement, filing
      and recording of the Plan of Merger in accordance with the requirements of
      the General


                                      -16-
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      Corporation Law of the State of Delaware and the Business Corporation Act
      of the State of Michigan (except that the officers of the Company may, at
      their election, file and record in the State of Delaware a Certificate of
      Ownership and Merger in accordance with the General Corporation Law of the
      State of Delaware and in the State of Michigan a Certificate of Merger in
      accordance with the Business Corporation Act of the State of Michigan in
      lieu of filing and recording the Plan of Merger); and it is further

            RESOLVED, that Houston National Bank be, and it hereby is, appointed
      to act as Exchange Agent in connection with the Merger to perform such
      duties as may be requested by the appropriate officers of the Company of
      Tenneco; and it is further

            RESOLVED, that the Memorandum of Instructions for the Exchange Agent
      in connection with the Merger (proof of July 22, 1977), a copy of which is
      before this Board, be, and the same hereby is, approved, and the President
      or any Vice President, and the Secretary or any Assistant Secretary, be,
      and they hereby are, authorized to execute and deliver such Memorandum of
      Instructions substantially in the form approved hereby, with such changes
      therein as the President or Vice President executing the same shall
      approve, his approval to be evidenced conclusively by his execution and
      delivery thereof; and it is further

            RESOLVED, that the officers of the Company be, and they hereby are,
      authorized and directed to execute and deliver such documents and
      certificates and take such action as they deem necessary or appropriate to
      perform the obligations of the Company under the Plan of Merger and to
      effect the merger contemplated thereby.

      FOURTH: Anything herein or elsewhere to the contrary notwithstanding this
merger may be terminated and abandoned by the Board of Directors of MAEC
CORPORATION at any time prior to the date of filing the merger with the
Secretary of State.

      IN WITNESS WHEREOF, said MAEC CORPORATION has caused this certificate to
be signed by E. L. Capps, its Vice President and attested by Gavin H. Smith, its
Assistant Secretary, this 25th day of July, 1977.

ATTEST:                                      MAEC CORPORATION


By /s/ Gavin H. Smith                        By  /s/ E. L. Capps
   -----------------------------                -------------------------------
   Assistant Secretary                          Vice President


                                      -17-
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                         CERTIFICATE OF INCORPORATION
                                       OF
                                MAEC CORPORATION

                                  * * * * * *


            1. The name of the corporation is

                                MAEC CORPORATION

            2. The address of its registered office in the State of Delaware is
No. 100 West Tenth Street, in the City of Wilmington, County of New Castle. The
name of its registered agent at such address is The Corporation Trust Company.

            3. The nature of the business or purposes to be conducted or
promoted is to engage in any lawful act or activity for which corporations may
be organized under the General Corporation Law of Delaware.

            4. The total number of shares of stock which the corporation shall
have authority to issue is two hundred (200) and the par value of each of such
shares is Five Dollars ($5.00) amounting in the aggregate to One Thousand
Dollars ($1,000).

            5A. The name and mailing address of each incorporator is as follows:






                                      -18-
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         NAME                                      MAILING ADDRESS
         ----                                      ---------------

      S. S. Simpson                             100 West Tenth Street
                                                Wilmington, Delaware 19801

      W. J. Reif                                100 West Tenth Street
                                                Wilmington, Delaware 19801

      R. F. Andrews                             100 West Tenth Street
                                                Wilmington, Delaware 19801

            5B. The name and mailing address of each person, who is to serve as
a director until the first annual meeting of the stockholders or until a
successor is elected and qualified, is as follows:

         NAME                                      MAILING ADDRESS
         ----                                      ---------------

      K. W. Reese                               P. O. Box 2511
                                                Houston, Texas 77001

      M. W. Meyer                               P. O. Box 2511
                                                Houston, Texas 77001

      E. L. Capps                               P. O. Box 2511
                                                Houston, Texas 77001

            6. The corporation is to have perpetual existence.

            7. In furtherance and not in limitation of the powers conferred by
statute, the board of directors is expressly authorized to make, alter or
repeal the by-laws of the corporation.

            8. Elections of directors need not be by written ballot unless the
by-laws of the corporation shall so provide.

            Meetings of stockholders may be held within or without the State of
Delaware, as the by-laws may provide. The books of the corporation may be kept
(subject to any provision contained in the statutes) outside the


                                      -19-
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State of Delaware at such place or places as may be designated from time to
time by the board of directors or in the by-laws of the corporation.

            9. The corporation reserves the right to amend, alter, change or
repeal any provision contained in this certificate of incorporation, in the
manner now or hereafter prescribed by statute, and all rights conferred upon
stockholders herein are granted subject to this reservation.

            WE, THE UNDERSIGNED, being each of the incorporators hereinbefore
named, for the purpose of forming a corporation pursuant to the General
Corporation Law of the State of Delaware, do make this certificate, hereby
declaring and certifying that this is our act and deed and the facts herein
stated are true, and accordingly have hereunto set our hands this 13th day of
July, 1977.

                                                    S. S. Simpson
                                             ---------------------------------
                                                    S. S. Simpson


                                                    W. J. Reif
                                             ---------------------------------
                                                    W. J. Reif


                                                    R. F. Andrews
                                             ---------------------------------
                                                    R. F. Andrews






                                      -20-