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                                                                  EXHIBIT 10.8.3



                               AMENDMENT NO. 5 TO
                              AMENDED AND RESTATED
                          LOAN AND SECURITY AGREEMENT

                        MAGNESIUM CORPORATION OF AMERICA
                               238 North 2200 West
                           Salt Lake City, Utah 84116



                                                                 August 10, 1999



Congress Financial Corporation
1133 Avenue of the Americas
New York, New York 10036


Gentlemen:

         Congress Financial Corporation ("Lender") and Magnesium Corporation of
America ("Borrower") have entered into certain financing arrangements pursuant
to the Amended and Restated Loan and Security Agreement, dated as of August 4,
1993, between Lender and Borrower, as amended pursuant to Amendment No. 1 to
Amended and Restated Loan and Security Agreement, dated January 31, 1996,
Amendment No. 2 to Amended and Restated Loan and Security Agreement, dated July
3, 1996, Amendment No. 3 to Amended and Restated Loan and Security Agreement,
dated August 28, 1997 and Amendment No. 4 Amended and Restated and Security
Agreement, dated January 19, 1999 (as further amended hereby and as the same may
hereafter be amended, modified, supplemented, extended, renewed, restated or
replaced, the "Loan Agreement", and together with all agreements, documents and
instruments at any time executed and/or delivered in connection therewith or
related thereto, collectively, the "Financing Agreements").

         Borrower has requested and certain additional amendments to the Loan
Agreement and Lender is willing to agree to such amendments, subject to the
terms and conditions contained herein. By this Amendment, Lender and Borrower
desire and intend to evidence such extension and amendments. All capitalized
terms used herein shall have the meaning assigned thereto in the other Financing
Agreements, unless otherwise defined herein.

         In consideration of the foregoing, and the respective agreements and
covenants contained herein, the parties hereto agree as follows:





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         1. Transactions with Affiliates.

                  (a) Section 7.6(b) of the Loan Agreement is hereby deleted in
its entirety and replaced with the following:

                  "(b) Borrower may (i) pay any dividend or any other
         distribution on account of any shares of any class of capital stock of
         Borrower now or hereafter outstanding, and (ii) make any loans or
         advance money or property to any such persons, (iii) guarantee, assume,
         endorse, or otherwise become responsible for (directly or indirectly)
         the Indebtedness, performance, obligations or dividends of any such
         person and (iv) make any payments in respect of any Indebtedness owing
         to Renco Metals (whether arising pursuant to payments made by Renco
         Metals on behalf of Borrower or otherwise); PROVIDED, THAT, in each
         case as to any of the foregoing, each of the following conditions is
         satisfied as determined by Lender:

                      (A) no Event of Default, or act, condition or event which
            with notice or passage of time or both would constitute an Event of
            Default shall have occurred and be continuing at the time of or
            after giving effect to any such payments or incurring any such
            obligations,

                      (B) any dividends or other distributions as described in
            Section 7.6(b)(i) above shall be out of funds legally available
            therefor, and

                      (C) as of the date of any such payments or the incurrence
            of any such obligations, as the case may be, the aggregate amount of
            all such payments made or such obligations incurred after July 3,
            1996 shall not exceed the amount equal to fifty (50%) percent of.
            (1) the cumulative Consolidated Net Income of Renco Metals (or if
            the Consolidated Net Income shall be a loss, MINUS one hundred
            (100%) percent of such loss) earned subsequent to July 3, 1996 and
            prior to the date the payment occur or the obligation is incurred
            (treating such period as a single accounting period) minus (2) all
            payments made or obligations incurred by Sabel during the same
            period and of the same type or nature described in Sections
            7.6(b)(i), 7.6(b)(ii) and 7.6(b)(iii) above or Section 7.6(j) below
            and all payments made by Borrower pursuant to Section 7.6(j) below
            for federal, state and local income taxes based on the taxable
            income of the immediately preceding fiscal year;"

                  (b) Section 7.6(c) of the Loan Agreement is hereby deleted in
its entirety and replaced with the following:

                  "(c) Borrower may make payments to Renco Group or an affiliate
         of Renco Group on behalf of Renco Metals pursuant to the tax sharing
         arrangement between Renco Metals and Renco Group (as in effect on the
         date hereof); PROVIDED, THAT, (i) Borrower is included in the
         consolidated federal income tax return filed by Renco Group or an
         affiliate of Renco Group as to which Borrower is making such payments
         for the 1998 tax year or any prior year, or for any taxable period
         during which Borrower joins with Renco






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         Group or an affiliate of Renco Group in filing any combined or
         consolidated (or similar) state or local income tax return for a
         jurisdiction which does not recognize Renco Metals and its Subsidiaries
         as QSSS (as defined in Section 7.6(j) hereof), (ii) the payments in any
         year shall not exceed the federal income tax liability that Borrower
         and its Subsidiaries would have been liable for if Borrower and its
         Subsidiaries had filed its tax returns on a stand-alone basis except
         that Borrower will not have the benefit of any of its tax loss
         carryforwards and any intercompany items shall, for tax liability
         purposes, be recorded on a cash basis rather than on an accrual basis,
         and (iii) such payments shall be made by Borrower no earlier than five
         (5) days prior to the date on which Renco Group or an affiliate of
         Renco Group is required to make its payments to the Internal Revenue
         Service or to a state or local jurisdiction described in Section
         7.6(c)(i) hereof;"

         (c) The following is hereby added as a new Section 7.6(j) to the Loan
Agreement:

                  "(j) With respect to any year that Renco Metals and its
         Subsidiaries have effectively been designated as qualified Subchapter S
         subsidiary companies ("QSSS") under the Code, Borrower may pay cash
         dividends to Renco Metals, from legally available funds therefor, to
         the extent taxable income of Borrower is required to be included in the
         taxable income shown by Renco Group as reported in its subchapter S tax
         returns ("Form 1120S"), subject to the following:

                      (A) Such cash dividends shall be in any such period, in an
            amount up to the product of (1) the taxable income of Borrower and
            its Subsidiaries for such period which is the basis for Renco Group
            being required to include such taxable income in its Form 1120S, as
            amended or modified or determined by audit, and the required
            estimated taxable income related thereto and the comparable state
            and local reports and estimated taxable income, multiplied by (2)
            the corporate Federal, State and local tax rates, whether calculated
            on regular taxable income or alternative minimum taxable income, as
            applicable, in effect for the taxable period applicable to Borrower
            and its Subsidiaries using the rates that would be applicable if
            Borrower and its Subsidiaries were not QSSS and calculated in
            accordance with the tax sharing arrangement between Renco Metals and
            Renco Group (as in effect on the date hereof),

                      (B) Borrower may pay such cash dividends for any period so
            long as (1) in such period, Renco Metals and its Subsidiaries are
            effectively designated QSSS, (2) the product of the taxable income
            of Borrower and its Subsidiaries for such period multiplied by the
            applicable tax rates as described above shall be reduced by any
            applicable tax credits or deductions calculated in accordance with
            the tax sharing arrangement between Renco Metals and Renco Group (as
            in effect on the date hereof) available to Borrower and its
            Subsidiaries which would reduce the amount of the income taxes
            payable by Borrower and its Subsidiaries, (3) any such dividends
            shall be paid no more than five (5) days prior to the date that
            Renco Group's shareholders are required to make payment of the taxes
            based on the taxable income of Renco Metals and its Subsidiaries,
            (4) not less than five (5) days prior to the payment of any such
            dividends, Lender shall have received a certificate signed by an
            officer of Borrower, in form and




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            substance satisfactory to Lender, stating the calculation of the
            amount which is the basis for tax distributions permitted hereunder
            through such period (if any) and providing full information and
            computations with respect thereto and (5) such dividend shall not be
            in violation of applicable law or any other agreement to which Renco
            Metals or Borrower are a party or by which Borrower or its assets
            are bound, and

                      (C) In no event shall dividends be paid to Renco Metals
            based on taxable income of Borrower and its Subsidiaries for
            jurisdictions which do not recognize Renco Metals and its
            Subsidiaries as QSSS and where (1) Borrower and its Subsidiaries are
            required to file and pay their individual taxes and (2) Renco Group
            is not required to pay, or by virtue of a consolidated (or similar)
            tax return does not make payments in respect of, the tax liabilities
            of Borrower or any of its Subsidiaries in such jurisdiction."

         2. Dividends. Section 7.7(b) of the Loan Agreement is hereby deleted in
its entirety and replaced with the following:

                  "(b) Borrower may pay dividends to Renco Metals to the extent
         permitted under Sections 7.6 (b) and 7.6 (j) hereof."

         3. Conditions Precedent. The effectiveness of the other terms and
provisions contained herein shall be subject to the receipt by Lender of an
original of this Amendment, duly authorized, executed and delivered by Borrower.

         4. Effect of this Agreement. Except as modified pursuant hereto, no
other changes or modifications in the Loan Agreement or the other Financing
Agreements are intended or implied and the Financing Agreements are hereby
specifically ratified, restated and confirmed by all parties hereto as of the
affective date hereof. To the extent of conflict between the terms of this
Amendment and the other Financing Agreements, the terms of this Amendment shall
control.

         5. Governing Law. The rights and obligations hereunder of each of the
parties hereto shall be governed by and interpreted and determined in accordance
with the laws of the State of New York.

         6. Binding Effect. This Amendment shall be binding upon and inure to
the benefit of each of the parties hereto and their respective successors and
assigns.

         7. Counterparts. This Amendment may be executed in any number of
counterparts, but all of such counterparts shall together constitute but one and
the same agreement. In making proof of this Amendment, it shall not be necessary
to produce or account for more than one counterpart thereof signed by each of
the parties hereto.






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         8. Further Assurances. The parties hereto shall execute and deliver
such additional documents and take such additional action as may be necessary or
desirable to effectuate the provisions and purposes of this Agreement.



                                             Very truly yours,


                                             MAGNESIUM CORPORATION OF AMERICA



                                             By:  /s/  Roger L. Fay
                                                 -------------------------------

                                             Title:  Vice President
                                                    ----------------------------


AGREED: CONGRESS FINANCIAL CORPORATION


By:  /s/  Janet S. Last
   --------------------------------

Title:  First Vice President
       ----------------------------