Document:

EXHIBIT 4.3

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                                 MASCOTECH, INC.

                                       AND

                  BANK ONE TRUST COMPANY, N.A. (as successor in
                interest to THE FIRST NATIONAL BANK OF CHICAGO),
                                     Trustee

                             ----------------------

                          Second Supplemental Indenture

                          Dated as of November 28, 2000
                             ----------------------

                    Indenture, Dated as of November 1, 1986,
        as supplemented and amended by the First Supplemental Indenture,
                           Dated as of August 5, 1994
                           Between MascoTech, Inc. and
       The First National Bank of Chicago, as successor Trustee to Morgan
                      Guaranty Trust Company of New York,
           Relating to the 4 1/2% Convertible Subordinated Debentures
                                    Due 2003

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<PAGE>

                          SECOND SUPPLEMENTAL INDENTURE

     SECOND SUPPLEMENTAL INDENTURE (this "Second Supplemental Indenture"), dated
as of November 28, 2000, between MascoTech, Inc., a Delaware corporation (the
"Company"), having its principal office at 21001 Van Born Road, Taylor, Michigan
48180, and Bank One Trust Company, N.A. (as successor in interest to The First
National Bank of Chicago), a national banking association as Trustee (the
"Trustee").

                                    RECITALS

     WHEREAS, the Company, formerly known as Masco Industries, Inc., heretofore
executed and delivered an Indenture, dated as of November 1, 1986 and a
Supplemental Indenture, dated as of August 5, 1994 (together, the "Indenture")
with the Trustee (capitalized terms used but not otherwise defined in this
Second Supplemental Indenture shall have the meanings ascribed to such terms in
the Indenture); and

     WHEREAS, pursuant to the Indenture, the Company issued and the Trustee
authenticated and delivered $345,000,000 aggregate principal amount of the
Company's 4 1/2% Convertible Subordinated Debentures Due 2003 (the "Convertible
Securities"); and

     WHEREAS, the Company has entered into a Recapitalization Agreement dated as
of August 1, 2000, between the Company and Riverside Company LLC, a Delaware
limited liability company ("Riverside"), as amended (the "Recapitalization
Agreement"), pursuant to which Riverside will merge with and into the Company
(the "Merger") with the Company continuing as the surviving corporation (the
"Surviving Corporation"); and

     WHEREAS, pursuant to the Recapitalization Agreement, on the date of the
Merger, each issued and outstanding share of common stock of the Company (other
than (x) shares constituting Restricted Stock (as defined in the
Recapitalization Agreement), (y) dissenting shares and (z) shares owned by any
subsidiary of the Company) shall be converted into the right to receive from the
Surviving Corporation cash in an amount equal to (i) $16.90 (the "Base Merger
Consideration") and (ii) all Merger Consideration Adjustments (as defined in the
Recapitalization Agreement) with respect to each share (other than shares
referred to in clauses (x), (y) and (z) above) (clauses (i) and (ii) together,
the "Merger Consideration"); and

<PAGE>
                                      -2-

     WHEREAS, pursuant to Section 3.06 of the Indenture, the parties hereto are
entering into this Second Supplemental Indenture to provide that the holder of
each Convertible Security outstanding at the time of the Merger shall have the
right thereafter, during the period such Convertible Security shall be
convertible as specified in Section 3.01 of the Indenture, to convert such
Convertible Security only into the Merger Consideration receivable at the
effective time of the Merger by a holder of common shares of the Company and as
adjusted thereafter pursuant to the Recapitalization Agreement; and

     WHEREAS, pursuant to Section 11.01 of the Indenture, the Company and the
Trustee may enter into this Second Supplemental Indenture without the consent of
any holders of the Convertible Securities; and

     WHEREAS, this Second Supplemental Indenture has been duly authorized by all
necessary corporate action on the part of the Company; and

     NOW, THEREFORE, the Company hereby covenants and agrees with the Trustee
for the equal and proportionate benefit of all holders of the Convertible
Securities, as follows:

                                   ARTICLE ONE

                      CONVERSION OF CONVERTIBLE SECURITIES

     Section 1.1. Amendment of Certain Sections of Indenture. Subject to the
other provisions hereof, and pursuant to Section 11.01(f) of the Indenture, the
Indenture is hereby amended and supplemented in the following respects:

          (a) Section 3.05 of the Indenture is hereby amended and supplemented
     by adding the following at the end thereof:

          "(j) From and after the effective time of the merger (the "Merger")
     pursuant to the Recapitalization Agreement dated as of August 1, 2000, as
     amended, by and between the Company and Riverside Company LLC, a Delaware
     limited liability company (the "Recapitalization Agreement"), the holder of
     each Convertible Security then outstanding shall have the right thereafter,
     during the period such Convertible Security shall be convertible as
     specified in Section 3.01, to convert each such Convertible Security only
     into

<PAGE>
                                      -3-

     (i) $16.90 (the "Base Merger Consideration") and (ii) all Merger
     Consideration Adjustments (as defined in the Recapitalization Agreement)
     with respect to each Exchanged Share (as defined in the Recapitalization
     Agreement) (clauses (i) and (ii) together, the "Merger Consideration");
     provided, however, that at such time after the Merger that any holder of
     Convertible Securities elects to convert such Convertible Securities
     pursuant to this Section 3.05(j), the Trustee shall notify the Company of
     such election and the Company shall provide to the Trustee, a certification
     (in the form of an Officer's Certificate) as to the amount of Merger
     Consideration then owed to such holder."

                                   ARTICLE TWO

                                  MISCELLANEOUS

     Section 2.1. Effect of Second Supplemental Indenture. Upon the execution
and delivery of this Second Supplemental Indenture by the Company and the
Trustee, the Indenture shall be supplemented in accordance herewith, and this
Second Supplemental Indenture shall form a part of the Indenture for all
purposes, and every holder of Securities heretofore or hereafter authenticated
and delivered under the Indenture shall be bound thereby; provided, however,
that Article 1 of this Second Supplemental Indenture shall be effective only
upon the effectiveness of the Merger.

     Section 2.2. Indenture Remains in Full Force and Effect. Except as
supplemented hereby, all provisions in the Indenture shall remain in full force
and effect.

     Section 2.3. Indenture and Second Supplemental Indenture Construed
Together. This Second Supplemental Indenture is an indenture supplemental to the
Indenture, and forms a part of the Indenture for all purposes.

     Section 2.4. Conflict with Trust Indenture Act. If and to the extent that
any provision of this Second Supplemental Indenture limits, qualifies or
conflicts with any provision included in the Indenture or this Second
Supplemental Indenture which is required to be included in the Indenture or this
Second Supplemental Indenture, as the case may be, by any of Sections 310
through 317, inclusive, of the Trust Indenture Act of 1939, such required
provision shall control.

     Section 2.5. Separability Clause. In case any provision in this Second
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality

<PAGE>
                                      -4-

and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby.

     Section 2.6. Effect of Headings. The Article and Section headings herein
are for convenience only and shall not affect the construction hereof.

     Section 2.7. Benefits of Second Supplemental Indenture, Etc. Nothing in
this Second Supplemental Indenture, express or implied, shall give to any
Person, other than the parties hereto and thereto and their successors
hereunder, any benefit or any legal or equitable right, remedy or claim under
this Second Supplemental Indenture.

     Section 2.8. Successors and Assigns. All covenants and agreements in this
Second Supplemental Indenture by the Company shall bind its successors and
assigns, whether so expressed or not.

     Section 2.9. Trustee Not Responsible for Recitals. The recitals contained
herein shall be taken as the statements of the Company, and the Trustee assumes
no responsibility for their correctness. The Trustee makes no representations as
to the validity or sufficiency of this Second Supplemental Indenture.

     Section 2.10. Certain Duties and Responsibilities of the Trustee. In
entering into this Second Supplemental Indenture, the Trustee shall be entitled
to the benefit of every provision of the Indenture relating to the conduct or
affecting the liability of or affording protection to the Trustee, whether or
not elsewhere herein so provided.

     Section 2.11. Governing Law. This Second Supplemental Indenture shall be
governed by and construed in accordance with the laws of the State of New York.

     Section 2.12. Counterparts. This Second Supplemental Indenture may be
executed in counterparts, each of which, when so executed, shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

                            [Signature Page Follows]

<PAGE>
                                      -5-

     IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental
Indenture to be duly executed and attested, all as of the date and year first
above written.

                               MASCOTECH, INC.

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

Attest:

------------------------------
Title:
        ----------------------

                                BANK ONE TRUST COMPANY, N.A. (as successor in
                                interest to THE FIRST NATIONAL BANK OF CHICAGO),
                                as Trustee

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

Attest:

------------------------------
Title:
        ----------------------EXHIBIT 4.4

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                                MASCOTECH, INC.,

                              METALYNC COMPANY LLC

                                       AND

                  BANK ONE TRUST COMPANY, N.A. (as successor in
                interest to THE FIRST NATIONAL BANK OF CHICAGO),
                                     Trustee

                             ----------------------

                          Third Supplemental Indenture

                          Dated as of November 28, 2000
                             ----------------------

                    Indenture, Dated as of November 1, 1986,
                    as supplemented and amended by the First
           Supplemental Indenture, Dated as of August 5, 1994, and the
          Second Supplemental Indenture, Dated as of November 28, 2000
                           Between MascoTech, Inc. and
       The First National Bank of Chicago, as successor Trustee to Morgan
                      Guaranty Trust Company of New York,
           Relating to the 4 1/2% Convertible Subordinated Debentures
                                    Due 2003

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<PAGE>

                          THIRD SUPPLEMENTAL INDENTURE

     THIRD SUPPLEMENTAL INDENTURE (this "Third Supplemental Indenture"), dated
as of November 28, 2000, between MascoTech, Inc., a Delaware corporation (the
"Company"), Metalync Company LLC, a Delaware limited liability company and a
wholly-owned subsidiary of the Company ("Metalync"), both having their principal
offices at 21001 Van Born Road, Taylor, Michigan 48180, and Bank One Trust
Company, N.A. (as successor in interest to The First National Bank of Chicago),
a national banking association as Trustee (the "Trustee").

                                    RECITALS

     WHEREAS, the Company, formerly known as Masco Industries, Inc., heretofore
executed and delivered an Indenture, dated as of November 1, 1986, a
Supplemental Indenture, dated as of August 5, 1994, and a Second Supplemental
Indenture, dated as of November 28, 2000 (together, the "Indenture") with the
Trustee (capitalized terms used but not otherwise defined in this Third
Supplemental Indenture shall have the meanings ascribed to such terms in the
Indenture); and

     WHEREAS, pursuant to the Indenture, the Company issued and the Trustee
authenticated and delivered $345,000,000 aggregate principal amount of the
Company's 4 1/2% Convertible Subordinated Debentures Due 2003 (the
"Convertible Securities"); and

     WHEREAS, pursuant to Section 11.01(g) of the Indenture, Metalync, the
Company and the Trustee may enter into this Third Supplemental Indenture without
the consent of any holders of the Convertible Securities to make provisions in
regard to matters arising under the Indenture which do not materially adversely
affect the interests of the holders of Securities; and

     WHEREAS, the Company will assign certain of its assets to Metalync; and

     WHEREAS, Metalync and the Company desire to join Metalync as a party to the
Indenture pursuant to Section 12.01 of the Indenture; and

<PAGE>
                                      -2-

     WHEREAS, this Third Supplemental Indenture has been duly authorized by all
necessary corporate action on the part of Metalync and the Company; and

     NOW, THEREFORE, Metalync and the Company hereby covenant and agree with the
Trustee for the equal and proportionate benefit of all holders of the
Convertible Securities, as follows:

                                   ARTICLE ONE

                                    AMENDMENT

     Section 1.1. Amendment of Certain Sections of Indenture. Subject to the
other provisions hereof, and pursuant to Section 11.01(g) of the Indenture, the
Indenture is hereby amended and supplemented in the following respects:

     (a) Section 3.06(a) of the Indenture is hereby amended by deleting the text
contained in the third line of subpart (a) thereof and replacing it with the
following:

     "continuing corporation or limited liability company and which does not
     result in any reclassification of, or"

     (b) Section 3.06(b) of the Indenture is hereby amended by deleting the text
contained in the first two lines of subpart (b) thereof and replacing it with
the following:

     "(b) any sale or conveyance to another corporation or limited liability
     company of the assets of the Company as an entirety or substantially"

     (c) Section 11.01(a) of the Indenture is hereby amended by deleting the
text thereof and replacing it with the following:

     "(a) to evidence the succession of another corporation or limited liability
     company to the Company, or successive succession, and the assumption by the
     successor corporation or limited liability company of the covenants,
     agreements and obligations of the Company pursuant to Article Twelve
     hereof;"

<PAGE>
                                      -3-

     (d) Section 12.01 of the Indenture is hereby amended by deleting the text
thereof and replacing it with the following:

     "SECTION 12.01. Consolidation, Merger and Sale of Assets Permitted. The
     Company covenants and agrees that it will not consolidate with, merge into,
     or sell or otherwise dispose of all or substantially all of its property as
     an entirety to, any person other than a corporation or a limited liability
     company organized under the laws of the United States of America or any
     State or Territory thereof or of the District of Columbia, lawfully
     entitled to acquire the same. The Company will not so consolidate or merge,
     or make any such sale or other disposition, unless, and the Company
     covenants and agrees that any such consolidation, merger, sale or other
     disposition shall be on the condition that, (1) the provisions of Section
     3.06 are complied with and (2) such corporation or limited liability
     company shall expressly assume the due and punctual payment of the
     principal of and premium, if any, and interest on all the Securities,
     accordingly to their tenor, and the due and punctual performance and
     observance of all of the covenants and conditions of this Indenture to be
     performed by the Company, by supplemental indenture satisfactory to the
     Trustee, executed and delivered to the Trustee by such corporation or
     limited liability company. The Company covenants and agrees that it will
     not so consolidate or merge or make any such sale or other disposition, or
     permit any corporation to merge into the Company, if immediately thereafter
     the Company or such successor corporation or limited liability company, as
     the case may be, shall be in default in the performance or observance of
     any of the covenants or conditions of this Indenture.

     (d) Section 12.02 of the Indenture is hereby amended by deleting the text
thereof and replacing it with the following:

     "SECTION 12.02 Successor Corporation or Limited Liability Company to Be
     Substituted for Company. In case of any such merger, consolidation, sale or
     conveyance and upon any such assumption by the successor corporation or
     limited liability company, such successor corporation or limited liability
     company shall succeed to and be substituted for the Company, with the same
     effect as if it had been named herein as the party of the first part, and,
     in case of such a sale or conveyance other than a lease, the Company
     thereupon shall be relieved of any further obligation or liability
     hereunder or upon the Securities, and may thereupon or at any time
     thereafter be dissolved, wound up or

<PAGE>
                                      -4-

     liquidated. Such successor corporation or limited liability company
     thereupon may cause to be signed, and may issue either in its own name or
     in the name of MascoTech, Inc. any or all of the Securities issuable
     hereunder which theretofore shall not have been signed by the Company and
     delivered to the Trustee or Authenticating Agent; and, upon the order of
     such successor corporation or limited liability company (instead of the
     Company) and subject to all the terms, conditions and limitations in this
     Indenture prescribed, the Trustee or the Authenticating Agent shall
     authenticate and deliver any Securities which previously shall have been
     signed and delivered by the officers of the Company to the Trustee or the
     Authenticating Agent for authentication, and any Securities which such
     successor corporation or limited liability company thereafter shall cause
     to be signed and delivered to the Trustee or the Authenticating Agent for
     that purpose. All the Securities so issued shall in all respects have the
     same legal rank and benefit under this Indenture as the Securities
     theretofore or thereafter issued in accordance with the terms of this
     Indenture as though all of such Securities had been issued at the date of
     the execution hereof.

          In case of any such consolidation, merger, sale or conveyance, such
     changes in phraseology and form (but not in substance) may be made in the
     Securities thereafter to be issued as may be appropriate."

     (e) Section 14.01 of the Indenture is hereby amended by deleting the text
thereof and replacing it with the following:

     "SECTION 14.01. Indenture and Securities Solely Obligations of Company and
     Any Successor Corporation or Limited Liability Company. No recourse for the
     payment of the principal of or premium, if any, or interest on any
     Security, or for any claim based thereon or otherwise in respect thereof,
     and no recourse under or upon any obligation, covenant or agreement of the
     Company in this Indenture or in any supplemental indenture, or in any
     Security, or because of the creation of any indebtedness represented
     thereby, shall be had against any incorporator, stockholder or other
     interestholder, officer, director, manager or member, as such, past,
     present or future of the Company or of any successor corporation or limited
     liability company of the Company, either directly or through the Company or
     any successor corporation or limited liability company of the Company,
     whether by virtue of any constitution, statute or rule of law, or by the
     enforcement of any assessment or penalty or

<PAGE>
                                      -5-

     otherwise; it being expressly understood that all such liability is hereby
     expressly waived and released as a condition of, and as a consideration
     for, the execution of this Indenture and the issue of the Securities."

     (f) Section 15.02 of the Indenture is hereby amended by deleting the text
thereof and replacing it with the following:

     "SECTION 15.02. Official Acts by Successor Corporation or Limited Liability
     Company. Any act or proceeding by any provision of this Indenture
     authorized or required to be done or performed by any board, committee or
     officer of the Company shall and may be done and performed with the like
     force and effect by the like board, member, committee, manager or officer
     of any corporation or limited liability company that shall at the time be
     the lawful sole successor of the Company."

                                   ARTICLE TWO

                                   ASSUMPTION

     Section 2.1. For value received, pursuant to Section 12.01 of the
Indenture, Metalync hereby jointly and severally assumes the due and punctual
payment of the principal of and premium, if any, and interest on all of the
Convertible Securities, according to their tenor, and the due and punctual
performance and observance of all of the covenants and conditions of the
Indenture on the part of the Company to be performed or observed.

     Section 2.2. Metalync shall join, and may exercise every right and power
of, the Company under the Indenture with the same effect as if Metalync had been
named along with the Company therein.

<PAGE>
                                      -6-

                                  ARTICLE THREE

                                  MISCELLANEOUS

     Section 3.1. Effect of Third Supplemental Indenture. Upon the execution and
delivery of this Third Supplemental Indenture by Metalync, the Company and the
Trustee, the Indenture shall be supplemented in accordance herewith, and this
Third Supplemental Indenture shall form a part of the Indenture for all
purposes, and every holder of Securities heretofore or hereafter authenticated
and delivered under the Indenture shall be bound thereby; provided, however,
that Article 1 and Article 2 of this Third Supplemental Indenture shall be
effective only upon the consummation of the transactions contemplated by the
Contribution Agreement dated as of November 28, 2000 between the Company and
Metalync.

     Section 3.2. Indenture Remains in Full Force and Effect. Except as
supplemented hereby, all provisions in the Indenture shall remain in full force
and effect.

     Section 3.3. Indenture and Third Supplemental Indenture Construed Together.
This Third Supplemental Indenture is an indenture supplemental to the Indenture,
and forms a part of the Indenture for all purposes.

     Section 3.4. Conflict with Trust Indenture Act. If and to the extent that
any provision of this Third Supplemental Indenture limits, qualifies or
conflicts with any provision included in the Indenture or this Third
Supplemental Indenture which is required to be included in the Indenture or this
Third Supplemental Indenture, as the case may be, by any of Sections 310 through
317, inclusive, of the Trust Indenture Act of 1939, such required provision
shall control.

     Section 3.5. Separability Clause. In case any provision in this Third
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

     Section 3.6. Effect of Headings. The Article and Section headings herein
are for convenience only and shall not affect the construction hereof.

     Section 3.7. Benefits of Third Supplemental Indenture, Etc. Nothing in this
Third Supplemental Indenture, express or implied, shall give to any Person,
other than

<PAGE>
                                      -7-

the parties hereto and thereto and their successors hereunder, any
benefit or any legal or equitable right, remedy or claim under this Third
Supplemental Indenture.

     Section 3.8. Successors and Assigns. All covenants and agreements in this
Third Supplemental Indenture by Metalync and the Company shall bind their
successors and assigns, whether so expressed or not.

     Section 3.9. Trustee Not Responsible for Recitals. The recitals contained
herein shall be taken as the statements of Metalync and the Company, and the
Trustee assumes no responsibility for their correctness. The Trustee makes no
representations as to the validity or sufficiency of this Third Supplemental
Indenture.

     Section 3.10. Certain Duties and Responsibilities of the Trustee. In
entering into this Third Supplemental Indenture, the Trustee shall be entitled
to the benefit of every provision of the Indenture relating to the conduct or
affecting the liability of or affording protection to the Trustee, whether or
not elsewhere herein so provided.

     Section 3.11. Governing Law. This Third Supplemental Indenture shall be
governed by and construed in accordance with the laws of the State of New York.

     Section 3.12. Counterparts. This Third Supplemental Indenture may be
executed in counterparts, each of which, when so executed, shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

                            [Signature Page Follows]

<PAGE>
                                      -8-

     IN WITNESS WHEREOF, the parties hereto have caused this Third Supplemental
Indenture to be duly executed and attested, all as of the date and year first
above written.

                                   METALYNC COMPANY LLC

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

Attest:

----------------------------------
Title:
        --------------------------

                                   MASCOTECH, INC.

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

Attest:

----------------------------------
Title:
        --------------------------

                                   BANK ONE TRUST COMPANY, N.A. (as successor
                                   in interest to THE FIRST NATIONAL BANK OF
                                   CHICAGO), as Trustee

                                   By:
                                            ------------------------------------
                                   Title:
                                            ------------------------------------
Attest:

-----------------------------------
Title:
        ---------------------------

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