<PAGE>   1
                                  Exhibit 10.6
                                  ------------



                          AMCAST INDUSTRIAL CORPORATION
                      FIRST MASTER BENEFIT TRUST AGREEMENT

                                 March 11, 1988





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                               TABLE OF CONTENTS
                               -----------------
                                                                    Page
                                                                    ----
ARTICLE I       Name of Trust ........................................2

        1.1     Name .................................................2
        1.2     Purpose ..............................................2

ARTICLE II      Definitions ..........................................2

ARTICLE III     The Plans ............................................4

ARTICLE IV      Payment Schedules under Plans ........................4

        4.1     Payment Schedules ....................................4
        4.2     Modified Payment Schedules ...........................5
        4.3     Withholdings .........................................5
        4.4     Further Assurances ...................................5
        4.5     Distributions in the Event
                of Taxability ........................................5

ARTICLE V       The Trust Fund and Funding ...........................6

        5.1     Receipt and Holding of
                the Trust Fund .......................................6
        5.2     Initial Funding of Trust .............................6
        5.3     Additional Funding; Excess Assets ....................7
        5.4     Release of Trust Funds Unless
                a Change of Control Occurs ...........................7
        5.5     Transfer to Another Trustee ..........................8

ARTICLE VI      Status of Trust ......................................8

        6.1     Grantor Trust ........................................8
        6.2     Subject to Claims of Creditors
                of the Company .......................................8
        6.3     Notification of Bankruptcy
                or Insolvency ........................................9

ARTICLE VII     The Trustee's Accounting ............................10

        7.1     Books and Records ...................................10
        7.2     Trustee's Report ....................................10
        7.3     Additional Reports ..................................10

ARTICLE VIII    Administration of the Trust Fund ....................11

        8.1     Ownership and Investment
                of the Trust Fund ...................................11
        8.2     Powers of the Trustee ...............................11
        8.3     Situs of Assets .....................................12
        8.4     Entire Agreement ....................................12

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<PAGE>   3


ARTICLE IX      Relating to the Trustee ..............................12

        9.1     Liability of the Trustee .............................12
        9.2     Obligations under Law ................................13
        9.3     Bond .................................................13
        9.4     Compensation .........................................13
        9.5     Indemnification ......................................13

ARTICLE X       Missing Persons, Incapacitated Executives,
                Death and Directions .................................14

        10.1    Missing Persons ......................................14
        10.2    Incapacitated Executives .............................14
        10.3    Death of Executive ...................................14
        10.4    Form .................................................14
        10.5    Proof of any Matter ..................................15
        10.6    Absence of Directions ................................15

ARTICLE XI      Resignation or Removal of Trustee ....................15

        11.1    Successor Trustee ....................................15
        11.2    Final Account ........................................15
        11.3    Transfer and Discharge ...............................15
        11.4    Effective Date of Appointment
                of Successor Trustee .................................16
        11.5    Merger or Consolidation ..............................16

ARTICLE XII     Protection for Third Persons .........................16

        12.1    Protection for Third Persons .........................16

ARTICLE XIII    Termination; Amendment; and Waiver ...................16

        13.1    Termination ..........................................16
        13.2    Amendment and Waiver .................................16
        13.3    Schedule A to the Trust ..............................17

ARTICLE XIV     General Provisions ...................................17

        14.1    Ohio Trust ...........................................17
        14.2    severability .........................................17
        14.3    Arbitration ..........................................18
        14.4    Notices ..............................................18
        14.5    Trust Beneficiaries ..................................18
        14.6    Headings .............................................18
        14.7    Counterparts .........................................19


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<PAGE>   4

                         AMCAST INDUSTRIAL CORPORATION
                         -----------------------------

                      FIRST MASTER BENEFIT TRUST AGREEMENT
                      ------------------------------------


     THIS FIRST MASTER BENEFIT TRUST AGREEMENT (the "Trust") is established this
11th day of March 1988 by AMCAST INDUSTRIAL CORPORATION, an Ohio corporation, as
grantor (the "Company"), and BANK ONE, DAYTON, NATIONAL ASSOCIATION, as trustee
(the "Trustee"), under the following circumstances:

          (A) The Company from time to time establishes incentive and other
     compensation plans and arrangements under which the Company becomes
     obligated to make deferred payments to present and former directors and
     executives of the Company;

          (B) The aforesaid compensation arrangements are not funded or
     otherwise secured, and the Company by this Trust desires to provide further
     assurance to Leo W. Ladehoff in connection with certain deferred payments
     provided for in the Executive Employment Agreement between Mr. Ladehoff and
     the Company dated October 29, 1986 and to other such persons that in the
     event of a Change of Control of the Company (as defined at Article II) such
     deferred payments will be timely made when due by depositing with the
     Trustee upon the occurrence of a Potential Change of Control of the
     Company, subject only to the claims of the Company's existing or future
     general creditors in the event of the Company's insolvency or bankruptcy as
     defined at Section 6.3, assets for use in making such deferred payments;

          (C) The Company desires to establish this Trust as a master trust
     arrangement and intends from time to time (i) to designate on Schedule A to
     this Trust, in addition to the aforesaid Executive Employment Agreement,
     such other plans and arrangements giving rise to deferred payment
     obligations of the Company that the Trustee is authorized to pay on behalf
     of the Company from Trust assets in the event of a Change of Control and
     (ii) to set forth on Schedule A to this Trust, in addition to Mr. Ladehoff,
     other persons for whose benefit this Trust is established and the Company's
     payment obligations to each such person; and

          (D) The Company desires for record keeping purposes only that the
     Trustee maintain a separate account for each such person and for investment
     purposes that the Trustee commingle the Trust assets;

     NOW, THEREFORE, in consideration of the mutual agreements contained herein
and for other good and valuable considerations, the parties hereto agree as
follows: 


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                                   ARTICLE I
                                   ---------

                                 NAME OF TRUST
                                 -------------

     1.1 NAME. This Trust may be referred to as the "First Master Benefit Trust
for Amcast Industrial Corporation."

     1.2 PURPOSE. This Trust is established for the purposes set forth in
Preambles A through D to this Trust.

                                   ARTICLE II
                                   ----------

                                  DEFINITIONS
                                  -----------

     The following terms used in this Trust shall have the following meanings:

     A. "Board" means the Board of Directors of the Company.

     B. "Change of Control" means and shall be deemed to have occurred on (i)
the date upon which the Company is provided a copy of a Schedule 13D, filed
pursuant to Section 13(d) of the Securities Exchange Act of 1934 (the "1934
Act"), indicating that a group or person, as defined in Rule 13d-3 under the
1934 Act, has become the beneficial owner of 20% or more of the outstanding
Voting Shares of the Company or the date upon which the Company first learns
that a person or group has become the beneficial owner of 20% or more of the
outstanding Voting Shares of the Company if a Schedule 13D is not filed; (ii)
the date of a change in the composition of the Board of Directors of the Company
such that individuals who were members of the Board of Directors on the date two
years prior to such change (or who were subsequently elected to fill a vacancy
in the Board, or were subsequently nominated for election by the Company's
shareholders, by the affirmative vote of at least two-thirds of the directors
then still in office who were directors at the beginning of such two year
period) no longer constitute a majority of the Board of Directors of the
Company; (iii) the date the shareholders of the Company approve a merger or
consolidation of the Company with any other corporation, other than a merger or
consolidation which would result in the Voting Shares of the Company outstanding
immediately prior thereto continuing to represent (either by remaining
outstanding or by being converted into Voting Shares of the surviving entity) at
least 80% of the total voting power represented by the voting shares of the
Company or such surviving entity outstanding immediately after such merger or
consolidation; or (iv) the date shareholders of the





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Company approve a plan of complete liquidation of the Company or an agreement
for the sale or disposition by the Company of all or substantially all the
Company's assets.

     C. "Company" means Amcast Industrial Corporation, an Ohio corporation, and
any successor to such entity.

     D. "Executive" means and includes Leo W. Ladehoff and any other person who
in accordance with the terms of a Plan is or was a participant in a Plan and who
is listed on Schedule A to this Trust as a person to whom the Trustee by the
terms of this Trust is directed to make payments on behalf of the Company.

     E. "Executive Employment Agreement" means the Executive Employment
Agreement between the Company and Leo W. Ladehoff dated October 29, 1986.

     F. "Fiscal Year" means the fiscal year of the Company.

     G. "Payment Schedule" shall have the meaning ascribed to it at Section 4.1.

     H. "Plans" means the Executive Employment Agreement and those other
compensation arrangements, plans or agreements listed on Schedule A to this
Trust under which the Company is obligated to make payments to individual
Executives and the Trustee under this Trust is directed to make such payments on
behalf of the Company.

     I. "Potential Change of Control" means and shall be deemed to have occurred
if (i) Voting Shares of the Company have been acquired other than directly from
the Company in exchange for cash or property by any person who thereby becomes
the owner of more than 15% of the Company's outstanding Voting Shares; (ii) any
person (other than the Company) has made a tender offer for, or a request for
invitations for tenders of, Voting Shares; (iii) any person forwards or causes
to be forwarded to shareholders of the Company proxy statement(s) in any period
of twenty-four (24) consecutive months, soliciting proxies to elect to the Board
of Directors of the Company two or more candidates who were not nominated as
candidates in proxy statements forwarded to shareholders during such period by
the Board of Directors of the Company; or (iv) the Board adopts a resolution to
the effect that, for purposes of this Agreement, a Potential Change of Control
of the Company has occurred.


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     J. "Trust" means the trust created by this Agreement.

     K. "Trust Fund" shall have the meaning ascribed to it at Section 5.1.

     L. "Trustee" means any trustee from time to time serving as the trustee of
the Trust.

     M. "Voting Shares" means any securities of the Company which vote generally
in the election of directors.

                                  ARTICLE III
                                  -----------

                                   THE PLANS
                                   ---------

        The Trustee shall, on behalf of the Company and out of the Trust Fund,
make payments to the Executives in accordance with the Payment Schedules
delivered to the Trustee pursuant to Article IV. The Company shall continue to
be liable to make all payments to Executives required under the terms of the
Plans to the extent such payments have not been made pursuant to this Trust.
Payments made from the Trust Fund to Executives in respect of the Plans pursuant
to Article IV shall, to the extent of such payments, satisfy the Company's
obligation to pay benefits to such Executives under the Plans.


                                   ARTICLE IV
                                   ----------

                         PAYMENT SCHEDULES UNDER PLANS
                         -----------------------------

        4.1 PAYMENT SCHEDULES. Upon or before the occurrence of a Potential
Change of Control, the Company shall provide the Trustee with a schedule of the
individual Executives who are participants in the Plans listed on Schedule A and
to whom payments are to be made from the Trust on behalf of the Company. Upon
the occurrence of a Potential Change of Control, the Company shall also deliver
to the Trustee payment schedules, included as Part II to Schedule A, showing as
to each Executive the dates payments are to be made to each individual Executive
and the amount of each such payment or setting forth a formula or instructions
acceptable to the Trustee for determining the amounts so payable and the payment
dates ("Payment Schedules"). The Payment Schedules shall include instructions as
to the amount of interest accruing under the Plan. The Payment Schedules, as
they pertain to each Executive, shall also be delivered by the Company to such
Executive.


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<PAGE>   8

        4.2 MODIFIED PAYMENT SCHEDULES. Modified Payment Schedules shall be
delivered by the Company to the Trustee and to each Executive (as it pertains to
such Executive) each time that additional amounts are required to be paid by the
Company to the Trustee under Section 5.3 and upon the occurrence of any event,
such as early retirement of an Executive, requiring a modification of the
Payment Schedule. The Trustee shall make payments from the Trust assets to an
Executive in accordance with the provisions of the Payment Schedule applicable
to such Executive. In the event that an Executive reasonably believes that the
Payment Schedule, as modified, does not properly reflect the amount payable to
such Executive or the time or form of payment from the Trust assets in respect
of any Plan, such Executive shall be entitled to deliver to the Trustee written
notice (the "Executive's Notice") setting forth payment instructions for the
amount the Executive believes is payable under the relevant terms of such Plan.
The Executive shall also deliver a copy of the Executive's Notice to the Company
within three (3) business days of the delivery to the Trustee. Unless the
Trustee receives written objection from the Company within thirty (30) business
days after receipt by the Trustee of such notice, the Trustee shall make the
payment in accordance with the payment instructions set forth in the Executive's
Notice. In the event the Company delivers to the Trustee a written objection in
accordance with the preceding sentence, then, if the Company and the Executive
are unable to resolve their differences within the 45-day period following the
Company's delivery of objections to the Trustee, the parties shall submit the
matter to arbitration in accordance with Section 14.3.

        4.3 WITHHOLDINGS. The Trustee shall be permitted to withhold from any
payment due to an Executive hereunder the amount required by law to be so
withheld under Federal, state and local wage withholdings requirements or
otherwise, and shall pay over to the appropriate government authority the
amounts so withheld. The Trustee may rely on instructions from the Company as to
any required withholding and shall be fully protected under Section 9.5 in
relying on such instructions.

        4.4 FURTHER ASSURANCES. The Trustee shall, at any time and from time to
time, administer this Trust as may be necessary or proper to effectuate the
purposes of this Trust. If the Trust receives an unqualified opinion of tax
counsel selected by the Trustee, which opinion states that the Executives are
subject to Federal income tax on amounts held in Trust prior to the distribution
to the Executives of such amounts, the Trustee shall, to the extent practicable,
take such action and administer the Trust Fund in such a manner so as to prevent
the Trust Fund from being immediately taxable income to the Executives before
making



                                      134
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any distributions pursuant to Section 4.5, provided that the Trustee shall not
return any portion of the Trust Fund to the Company.

        4.5 DISTRIBUTIONS IN THE EVENT OF TAXABILITY. In the event of any final
determination by the Internal Revenue Service or a court of competent
jurisdiction, which determination is not appealable or the time for appeal or
protest of which has expired, or the receipt by the Trustee of a substantially
unqualified opinion of tax counsel selected by the Trustee, which determination
determines, or which opinion opines, that the Executives or any particular
Executive, is subject to Federal income taxation on amounts held in the Trust
prior to the distribution to the Executives or Executive of such amounts and no
curative action is available under Section 4.4, the Trustee shall, on receipt by
the Trustee of such opinion or notice of such determination, pay to each
Executive the portion of the Trust Fund includible in such Executive's Federal
gross income, provided as a condition of receiving such payment, the Executive
delivers to the Trustee a written agreement stating that the payment being made
is in satisfaction of the obligations of the Company due to him in respect of
which the payment is made, after taking into consideration that such payment is
being made prior to the required distribution date, and the Company concurs in
such agreement which concurrence shall not be unreasonably withheld.


                                   ARTICLE V
                                   ---------

                           THE TRUST FUND AND FUNDING
                           --------------------------

        5.1 RECEIPT AND HOLDING OF THE TRUST FUND. The Trustee will accept and
hold all contributions and all insurance contracts, insurance policies and other
property transferred and delivered to the Trustee by the Company or at the
Company's direction. All contributions and property received by the Trustee,
plus income and appreciation, constitute the trust fund (the "Trust Fund").

        5.2 INITIAL FUNDING OF TRUST. Concurrently with the execution of this
Trust, the Company is delivering to the Trustee the sum of One Thousand Dollars
to be held in trust hereunder. Upon the occurrence of a Potential Change of
Control, the Company shall contribute to the Trust, in cash or other property,
the amount determined under accepted actuarial principles to be necessary to
fund the amounts payable to the Executives under the Plans in accordance with
the Payment Schedules for the Executives delivered to the Trustee pursuant to
Section 4.1.



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<PAGE>   10


        5.3 ADDITIONAL FUNDING; EXCESS ASSETS. Unless the Trust Funds
contributed to the Trustee pursuant to the last sentence of Section 5.2 have
been released to the Company pursuant to Section 5.4, the Company shall, as soon
as practicable after the end of each Fiscal Year, recalculate the amount
determined under accepted actuarial principles to be necessary to fund the
amounts payable to the Executives under all Plans and in accordance with the
Payment Schedules for the Executives delivered to the Trustee pursuant to
Section 4.1 and 4.2 through the end of the most recently completed Fiscal Year
(herein referred to as the "Aggregate Payment Obligation"). If the Aggregate
Payment Obligation exceeds the fair market value of the assets in the Trust at
the end of the most recently completed Fiscal Year, then there exists a funding
deficiency to the extent of such excess; and the Company shall by no later than
90 days after the end of such Fiscal Year contribute to the Trustee additional
cash or property having a fair market value equal to the amount of the funding
deficiency. If the fair market value of assets in the Trust at the end of the
most recently completed Fiscal Year is more than 125% of the Aggregate Payment
Obligation, then there is an overfunding to the extent of such excess; and the
Trustee shall as soon as practicable after the determination that an overfunding
exists distribute cash or other property to the Company having a fair market
value equal to the amount by which the fair market value of Trust assets exceeds
125% of the Aggregate Payment Obligation.

        5.4 RELEASE OF TRUST FUNDS UNLESS CHANGE OF CONTROL OCCURS. Any funds
delivered to the Trustee pursuant to Section 5.2 because of the occurrence of a
Potential change of Control, together with any assets in the Trust Fund in
excess of $1,000, shall be returned to the Company one year after the date of
such delivery, unless a Change of Control shall have occurred. If any subsequent
Potential Change of Control occurs during such initial one-year period, such
initial one-year period shall be extended to a date one year after the
occurrence of the subsequent Potential Change of Control. The Company shall
notify the Trustee of the occurrence of a Change of Control or Potential Change
of Control, and Executives holding 25% or more beneficial interest in Trust
Funds may notify the Trustee that a Change of Control or Potential Change of
Control has occurred (provided in the case of any such notice from Executives,
it is accompanied by an opinion of counsel stating that in the opinion of such
counsel a Change of Control or Potential Change of Control has occurred). The
Trustee may rely on any such notice or on any other actual notice satisfactory
to the Trustee of such a change or potential change which the Trustee may
receive. Notwithstanding the foregoing, the Trustee shall have no




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duty or obligation to make any independent determination that such a change or
potential change has occurred. In the event Trust Funds are released to the
Company pursuant to this Section 5.4, all payment schedules delivered to the
Trustee pursuant to Section 4.1 shall be returned to the Company and be of no
further force and effect.

        5.5 TRANSFER TO ANOTHER TRUSTEE. The Company may direct the Trustee to
transfer the Trust Fund to a successor trustee as set forth in Section 11.1. The
Trustee immediately will comply with that direction. When that transfer is
completed, the Trustee will be relieved from all further obligations in
connection with the Trust Fund.


                                   ARTICLE VI
                                   ----------

                                STATUS OF TRUST
                                ---------------

        6.1 GRANTOR TRUST. The Trust is part of the Company's program
established for the purpose of providing deferred compensation to its present
and former directors and key employees and is intended to be exempt from the
participation, vesting, funding and fiduciary requirements of the Employee
Retirement Income Security Act of 1974, as amended. The Company intends the
Trust to be treated as a grantor trust within the meaning of Section 671 of the
Internal Revenue Code and all income attributable to the Trust Fund shall be
reported by the Company. The Trust Fund shall at all times be subject to the
claims of the creditors of the Company as set forth in Section 6.2.

        6.2 SUBJECT TO CLAIMS CREDITORS OF THE COMPANY. It is the intent of the
parties hereto that the Trust Fund is and shall remain at all times subject to
the claims of the creditors of the Company in the event of the Company's
insolvency or bankruptcy as set forth in this Article VI, including, without
limitation, its general creditors. Accordingly, the Company shall not create a
security interest in the Trust Fund in favor of the Executives or any creditor.
If the Trustee receives the notice provided for in Section 6.3, or otherwise
receives actual notice that the Company is insolvent or bankrupt as defined in
Section 6.3, the Trustee will make no further distributions of the Trust Fund to
any of the Executives but shall deliver the entire amount of the Trust Fund only
as a court of competent jurisdiction, or duly appointed receiver or other person
authorized to act by such a court, may direct, in order to make the Trust Fund
available to satisfy the claims of the Company's creditors, including, without
limitation, its general creditors. The Trustee shall resume distribution of




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the Trust Fund to the Executives under the terms hereof, upon no less than
thirty (30) days advance notice to the Company, if it determines that the
Company was not, or is no longer, bankrupt or insolvent. Unless the Trustee has
actual notice of the Company's bankruptcy or insolvency, the Trustee shall have
no duty to inquire whether the Company is bankrupt or insolvent.

        6.3 NOTIFICATION OF BANKRUPTCY OR INSOLVENCY. The Company, through its
Board of Directors and Chief Executive Officer, shall advise the Trustee
promptly in writing of the Company's bankruptcy or insolvency. The Company shall
be deemed to be bankrupt or insolvent, for purposes of this Agreement only, upon
the occurrence of any of the following:

               (i) The Company shall make an assignment for the benefit of
          creditors, file a petition in bankruptcy, petition or apply to any
          tribunal for the appointment of a custodian, receiver, liquidator,
          sequestrator, or any trustee for it or a substantial part of its
          assets, or shall commence any case under any bankruptcy,
          reorganization, arrangement, readjustment of debt, dissolution, or
          liquidation law or statute of any jurisdiction (federal or state),
          whether now or hereafter in effect; or if there shall have been filed
          any such petition or application, or any such case shall have been
          commenced against it, in which an order for relief is entered or which
          remains undismissed; or the Company by any act or omission shall
          indicate its consent to, approval of or acquiescence in any such
          petition, application or case or order for relief or to the
          appointment of a custodian, receiver or any trustee for it or any
          substantial part of any of its property, or shall suffer any such
          custodianship, receivership, or trusteeship to continue undischarged;
          or

               (ii) The Company shall be unable to pay its obligations as they
          become due in the usual course of its affairs; or

               (iii) The sum of the Company's debts is greater than all its
          property at a fair valuation; or

               (iv) The present saleable value of the Company's assets is less
          than the amount that would be required to pay the probable liability
          on its existing debts as they become absolute and matured.


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<PAGE>   13




                                  ARTICLE VII
                                  -----------

                            THE TRUSTEE'S ACCOUNTING
                            ------------------------

     7.1 BOOKS AND RECORDS. The Trustee will keep accurate and detailed accounts
of all investments, receipts, disbursements and other transactions in respect of
the Trust Fund. Those accounts and related records may be inspected by any
person designated by the Company. The Trustee will retain those records and
supporting data for the period required by law. All Trust assets may be
commingled for purposes of investment. For recordkeeping purposes only, an
account will be maintained for each Executive. Each account will be credited
with all contributions relating to the Executive for whom it was established and
will be debited with all payments to such Executive.

     7.2 TRUSTEE'S REPORT. Within 60 days after the end of each Fiscal Year, the
Trustee shall file a written report with the Company containing:

          (a) A description of investments, receipts, disbursements and other
     transactions effected by the Trustee during the most recently completed
     Fiscal Year;

          (b) An exact description of any asset transferred to the Trustee or
     transferred by the Trustee to any other person during such Fiscal Year;

          (c) An exact description of assets sold or purchased by the Trustee
     during such Fiscal Year, the cost of each item purchased and the net
     proceeds of each item sold;

          (d) An exact description of all assets held by the Trustee as of the
     close of business on the last day of such Fiscal Year, and the cost and
     fair market value of each item (other than insurance contracts) determined
     as of the same date; and

          (e) Any other information required by law to be filed on behalf of the
     Trust.

     The information described in subsections (a), (b) and (c), above, may be
given in the form of monthly or quarterly reports, if those reports, taken
together, contain the required information.

     7.3 ADDITIONAL REPORTS. In addition to the report required under Section
7.2 above, the Trustee shall make any interim reports reasonably requested by
the Company.





                                      139
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                                  ARTICLE VIII
                                  ------------

                        ADMINISTRATION OF THE TRUST FUND
                        --------------------------------

     8.1 OWNERSHIP AND INVESTMENT OF THE TRUST FUND. The Trustee is the legal
owner of all Trust Fund assets and, subject to this Article, shall invest and
reinvest the Trust Fund. Any amounts reasonably necessary to meet contemplated
payments or to be transferred from the Trust Fund may be deposited temporarily
in the commercial department of any bank or trust company. The Trustee will not
be liable for any interest on those deposits except for interest actually paid
by the bank or trust company or, if the deposit is with the Trustee's own
commercial department, interest at the legally permitted rate agreed to by the
Trustee and the Company. Alternatively, the Trustee may make temporary deposits
in governmental obligations, certificates of deposit, commercial paper,
commercial paper master notes or a common trust fund maintained by the Trustee
for temporary cash investments.

     8.2 POWERS OF THE TRUSTEE. Subject to this Article, Article 5 and Sections
9.1 and 9.2 and in addition to the powers generally given to trustees by law,
the Trustee may:

          (a) Invest and reinvest the Trust Fund in (i) obligations issued or
     guaranteed by the United States or by any person controlled or supervised
     by and acting as an instrumentality of the United States pursuant to
     authority granted by Congress, (ii) obligations issued or guaranteed by any
     state or political subdivision thereof having a rating equal to or higher
     than the current A rating classification of Moody's Investors Service, Inc.
     or the current A rating classification of Standard & Poor's Corporation,
     both of New York, New York, or their successors; (iii) commercial or
     finance paper of any corporation having a net worth of $10,000,000 and
     having a rating classification equal to or higher than the current P-1
     rating classification of Moody's Investors Service, Inc. or the current A-1
     rating classification of Standard & Poor's Corporation, both of New York,
     New York, or their successors; (iv) bankers' acceptances drawn on and
     accepted by banks or trust companies organized under the laws of the United
     States of America or any state thereof, having a reported capital and
     surplus of at least $10,000,000 in dollars of the United States of America
     or bankers' acceptances drawn on and accepted by the Trustee; (v)
     certificates of deposit maturing within twelve months of



                                      140
<PAGE>   15



     the Trustee or of banks or trust companies, organized under the laws of the
     United States of America or any state thereof, having a reported capital
     and surplus of at least $10,000,000 in dollars of the United States of
     America and which has a rating at least equal to the rating required in
     (iii) above; and (vi) repurchase agreements collateralized with obligations
     described in (i) above; and (vii) money market funds the assets of which
     are of the types specified above; provided that any such investment or
     deposit is not prohibited by law.

          (b) Abandon, adjust, arbitrate, compromise, or otherwise settle any
     obligation or liability due to or from it as Trustee, including any tax
     claim, and/or enforce or contest any claim in legal or administrative
     proceedings. The Trustee will not be required to contest any claim unless
     it has been indemnified against the costs and expenses of that action or
     unless available Trust Fund assets are sufficient to pay those expenses.

          (c) Compensate from the Trust Fund, agents, accountants, brokers and
     counsel (who may be counsel for the Company) and other assistants and
     advisors which it believes are necessary or desirable for the proper
     administration of the Trust Fund.

          (d) Temporarily deposit uninvested funds in a commingled temporary
     deposit medium maintained by the Trustee, which is composed of certificates
     of deposit or other obligations issued by the Trustee.

          (e) Do all other acts not specifically mentioned above which are
     necessary to administer the Trust Fund and to carry out the purposes of the
     Trust.

     8.3 SITUS OF ASSETS. Except as permitted by law, the Trustee may not
maintain in the Trust Fund any assets located outside the jurisdiction of the
district courts of the United States.

     8.4 ENTIRE AGREEMENT. The Trustee will have only those powers, duties, or
responsibilities set forth in this Agreement.


                                   ARTICLE IX
                                   ----------

                            RELATING TO THE TRUSTEE
                            -----------------------

     9.1 LIABILITY OF THE TRUSTEE. The Trustee will exercise its powers and
perform its duties with the care, skill, prudence, and diligence under the
circumstances then prevailing



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that a prudent man acting in a like capacity and familiar with those matters
would use in the conduct of an enterprise of a like character and with like aim.
The Trustee also will diversify Trust Fund investments to minimize the risk of
large loss unless under the circumstances the Trustee believes it clearly would
be prudent not to diversify. Wherever this Trust Agreement provides that the
Trustee must follow directions of the Company or that the Trustee has no duty or
power concerning a matter, the Trustee will not be liable for any harm caused by
a direction or lack of a direction or by any exercise or non-exercise of power
by another unless:

          (a) the Trustee knowingly participates in or knowingly undertakes to
     conceal an act or omission of another fiduciary with respect to a Plan or
     the Trust; or

          (b) by the Trustee's failure to act in accordance with this Section,
     the Trustee has enabled another fiduciary to breach a fiduciary duty; or

          (c) the Trustee has knowledge of a breach of fiduciary duty which
     resulted in harm or injury and does not make reasonable efforts under the
     circumstances to remedy the breach.

     9.2 OBLIGATIONS UNDER LAW. Regardless of any general or specific power or
authority granted to it, the Trustee may not engage in any transaction, exercise
any power or perform any duty under this Trust in violation of the Internal
Revenue Code, Employee Retirement Income Security Act, as amended, or any
regulations or rulings issued under those laws.

     9.3 BOND. Unless required by law, the Trustee is not required to furnish
bond for the faithful performance of its duties.

     9.4 COMPENSATION. The Trustee will be compensated reasonably as agreed to
by the Company and the Trustee. That compensation and all reasonable expenses of
administration will be paid by the Company directly and not out of Trust Funds.

     9.5 INDEMNIFICATION. The Company agrees to indemnify and hold harmless the
Trustee from and against any and all damages, losses, claims or expenses as
incurred, including expenses of investigation and fees and disbursements of
counsel to the Trustee and any taxes imposed on the Trust Fund or income of the
Trust (the "Indemnified Amounts"), arising out of or in connection with the
performance by the Trustee of its duties hereunder provided the Indemnified
Amounts do not arise out of,



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<PAGE>   17


or are connected with, a harm as to which the Trustee may be liable under
subparagraphs (a), (b) or (c) of Section 9.1. Any amount payable to the Trustee
under this Section 9.5 and not previously paid by the Company shall be paid by
the Company promptly upon demand therefor by the Trustee.


                                   ARTICLE X
                                   ---------

        MISSING PERSONS, INCAPACITATED EXECUTIVES, DEATH AND DIRECTIONS
        ---------------------------------------------------------------

     10.1 MISSING PERSONS. If any payment to be made by the Trustee to an
Executive is not claimed or accepted by the Executive, the Trustee shall notify
the Company. The Trustee shall not have any obligation to search for or
ascertain the whereabouts of any Executive.

     10.2 INCAPACITATED EXECUTIVES. While a Executive who is entitled to a
payment or distribution hereunder is under a legal disability or, in the
Trustee's opinion, in any way is incapacitated so as to be unable to manage his
financial affairs, the Trustee may make any required distribution to an
Executive by making it (i) directly to the Executive, (ii) a legal guardian of
the Executive, or (iii) in such other manner as the Trustee deems in the best
interest of the Executive.

     10.3 DEATH OF EXECUTIVE. If any Plan designated on Schedule A provides for
the continuance of payments upon the death of Executive, the Trustee shall use
Trust Funds to make such payments. In the event an Executive dies before
receiving all payments required to be paid to him pursuant to the Payment
Schedules, the Company shall, within 30 days of Executive's death, provide the
Trustee with a new Payment Schedule relating to Executive directing the Trustee
as to whether future payments are to be made to a designated beneficiary of
Executive or Executive's estate or whether payments terminate upon death. In the
event a Plan provides that a designated beneficiary or the estate of Executive
shall receive payments after the death of Executive, then the Payment Schedule
furnished to the Trustee in connection with the Executive's death shall be
furnished to the designated beneficiary or the estate, as the case may be, and
the provisions of Section 4.2 shall apply in the event that any disagreement as
to a modified Payment Schedule arises.

     10.4 FORM. All directions, notices, certifications and amendments to the
Trust to be given by the Company will be in writing; if given by the Company,
they will be signed on behalf of the Company.





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<PAGE>   18


        10.5 PROOF OF ANY MATTER. If required by the Trustee, any matter may be
proved conclusively by certification by the Company. The Trustee also may accept
or require any other or further evidence it believes to be sufficient or
necessary.

        10.6 ABSENCE OF DIRECTIONS. If the Trustee believes that it must take
action under this Trust, it may act in its sole discretion unless direction is
provided under this Trust.


                                   ARTICLE XI
                                   ----------

                        RESIGNATION OR REMOVAL OF TRUSTEE
                        ---------------------------------

        11.1 SUCCESSOR TRUSTEE. The Trustee may resign and be discharged from
its duties hereunder at any time by giving notice in writing of such resignation
to the company and each Executive specifying a date (not less than thirty (30)
days after the giving of such notice) when such resignation shall take effect.
Promptly after such notice, the Company shall appoint a successor trustee, such
trustee to become Trustee hereunder upon the resignation date specified in such
notice. The Trustee shall continue to serve until its successor accepts the
trust and receives delivery of the Trust Fund. The Company may at any time
substitute a new trustee by giving thirty (30) days notice thereof to the
Trustee then acting. The Trustee and any successor thereto appointed hereunder
shall be a commercial bank which is not an affiliate of the Company, but which
is a national banking association or established under the laws of one of the
states of the United States, and which has equity in excess of $10,000,000.

        11.2 FINAL ACCOUNT. If the Trustee dies, resigns or is removed, and
unless the Company accepts without exception the Trustee's final account, the
Trustee (or his representative) may settle its account either (a) by beginning
an action to procure a judicial settlement or (b) by agreeing on a settlement
with the Company.

        11.3 TRANSFER AND DISCHARGE. If a successor trustee is appointed, the
Trustee will transfer the Trust Fund to the successor along with true copies of
all relevant records reasonably requested by the successor. The Trustee also
will execute all documents necessary to the transfer of the Trust Fund. When it
has completed those actions, the Trustee will not be further accountable for any
matters covered in its accounting.



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<PAGE>   19


        11.4 EFFECTIVE DATE OF APPOINTMENT OF SUCCESSOR TRUSTEE. Appointment of
a successor trustee will be effective when it delivers to the Company and to the
former trustee written acceptance of the appointment. When delivered, this Trust
will be interpreted as if the successor trustee had been originally named
Trustee. However, the successor trustee will not be liable or responsible for
anything done or omitted in the administration of the Trust before its
appointment.

        11.5 MERGER OR CONSOLIDATION. If the Trustee engages in a corporate
reorganization, the resulting corporation automatically will be the Trustee's
successor.


                                  ARTICLE XII
                                  -----------

                          PROTECTION FOR THIRD PERSONS
                          ----------------------------

        12.1 PROTECTION FOR THIRD PERSONS. In dealing with the Trustee, no one
other than the Company is required to inquire into the Trustee's authority to
take any action authorized by this Trust. Those persons may assume that the
Trustee is authorized to take any action which it undertakes and will not be
liable for any act done under written direction of the Trustee. Also, those
persons may assume that the Trustee is authorized to receive any money or
property paid to the Trustee, or paid under the Trustee's written direction.
Written certification by the Company of the Trustee's name will be conclusive
evidence that the Trustee is qualified to act as Trustee at the date of that
certification.


                                  ARTICLE XIII
                                  ------------

                       TERMINATION; AMENDMENT; AND WAIVER
                       ----------------------------------

        13.1 TERMINATION. This Trust shall be terminated upon the earliest of
any of the following events: (i) the exhaustion of the Trust Fund; or (ii) the
final payment of all amounts payable to all of the Executives pursuant to all
the Plans. Promptly upon termination of this Trust, any remaining portion of the
Trust Fund shall be paid to the Company.

        13.2 AMENDMENT AND WAIVER. This Trust is irrevocable and may not be
amended except by an instrument in writing signed on behalf of the parties
hereto together with the written consent of Executives having at least
sixty-five percent (65%) of all amounts then held in the Trust credited to their
accounts, except that in the event a proposed amendment relates only to
Executives participating

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<PAGE>   20

in one Plan, then the written consent of Executives required to adopt such an
amendment shall be determined on the basis of the assets held in Trust in
respect of that Plan and the interest of such Executives in such assets. The
parties hereto, together with the consent of Executives having at least
sixty-five percent (65%) of all amounts then held in the Trust credited to their
accounts, may at any time waive compliance with any of the agreements or
conditions contained herein. Any agreement on the part of a party hereto or an
Executive to any such waiver shall be valid if set forth in an instrument in
writing signed by or on behalf of such party or Executive. Notwithstanding the
foregoing, any such amendment or waiver may be made by written agreement of the
parties hereto without obtaining the consent of the Executives if such amendment
or waiver does not, in the opinion of counsel acceptable to the Trustee,
adversely affect the rights of the Executives hereunder. No amendment or waiver
relating to this Trust may be made which only affects a particular Executive
unless such Executive has agreed in writing to such amendment or waiver.

        13.3 SCHEDULE A TO THE TRUST. Schedule A lists those Plans which the
Company, pursuant to Section 4.1, has designated as a Plan with respect to which
the Trustee is authorized to make payments to Executives from the Trust Fund as
set forth in this Trust. The Company may from time to time, as set forth in
Section 4.1, amend Schedule A to include an additional Plan or Plans or to list
additional Executives. The Company shall not, however, amend Schedule A to
delete a Plan or Plans from Schedule A unless any such deletion has been
approved in the same manner and by the same consent of Executives as an
amendment is required to be approved under Section 13.2.


                                  ARTICLE XIV
                                  -----------

                               GENERAL PROVISIONS
                               ------------------

        14.1 OHIO TRUST. The Trust will be construed and enforced according to 
the laws of the State of Ohio and the United States.

        14.2 SEVERABILITY. In the event that any provision of this Trust or the
application thereof to any person or circumstances shall be determined by a
court of proper jurisdiction to be invalid or unenforceable to any extent, the
remainder of this Trust, or the application of such provision to persons or
circumstances other than those as to which it is held invalid or unenforceable,
shall not be affected thereby, and each provision of this Trust shall be valid
and enforced to the fullest extent permitted by law.


                                      146
<PAGE>   21

        14.3 ARBITRATION. Any dispute between the Executives and the Company or
the Trustee as to the interpretation or application of the provisions of this
Trust and amounts payable hereunder shall be determined exclusively by binding
arbitration in Dayton, Ohio, in accordance with the rules of the American
Arbitration Association then in effect. Judgment may be entered on the
arbitrator's award in any court of competent jurisdiction.

        14.4 NOTICES. Any notice, report, demand or waiver required or permitted
hereunder shall be in writing and shall be given personally or by prepaid
registered or certified mail, return receipt requested, addressed as follows:

     If to the Company:       Amcast Industrial Corporation
                              3931 South Dixie Avenue
                              Kettering, Ohio  45439
                              Attn:   Treasurer

     If to the Trustee:       Bank One, Dayton, National Association
                              Kettering Tower
                              7th Floor
                              Dayton, Ohio  45401
                              Attn:   Trust Department

If to an Executive, to the address of such Executive as listed next to his name
on Schedule A hereto.

        A notice shall be deemed received upon the date of delivery if given
personally or, if given by mail, upon the receipt thereof.

        14.5 TRUST BENEFICIARIES. Each Executive is an intended beneficiary
under this Trust, and shall be entitled to enforce all terms and provisions
hereof with the same force and effect as if such person had been a party hereto.

        14.6 HEADINGS. The headings and subheadings in this Agreement are
inserted for convenience of reference only and are not to be considered in the
construction of its provisions.



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<PAGE>   22


        14.7 COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which is an original; all counterparts constitute the same
instrument, sufficiently evidenced by any one counterpart.

        IN WITNESS WHEREOF, the Company and the Trustee have caused this
instrument to be executed this 11th day of March 1988.

                                     AMCAST INDUSTRIAL CORPORATION



Attest:                              By 
       --------------------------      --------------------------------
       Assistant Secretary           Title 
                                          -----------------------------
                                            "Company"



                                     BANK ONE, DAYTON, NATIONAL
                                      ASSOCIATION


                                     By  
                                       --------------------------------

                                                  "Trustee"






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<PAGE>   23


                                   SCHEDULE A
                         AMCAST INDUSTRIAL CORPORATION
                      FIRST MASTER BENEFIT TRUST AGREEMENT
                                 MARCH 11, 1988
                                 --------------


PLANS AS TO WHICH THE TRUSTEE HAS BEEN DESIGNATED TO MAKE
PAYMENTS ON BEHALF OF THE COMPANY.
---------------------------------------------------------

PLAN I: Executive Employment Agreement between Leo W.
        Ladehoff and the Company dated October 29, 1986 (the "Employment
        Agreement").

        l. Action of the Board of Directors of the Company.

        The Board of Directors of Amcast Industrial Corporation (the
        "Company") by resolutions adopted on December 16, 1987 directed that
        the Trustee be authorized to make the payments required to be made to
        Leo W. Ladehoff pursuant to Section 3 of the Executive Employment
        Agreement from the Trust Fund in the event a Change of Control occurs
        and the Trust is funded as provided in Article V.

        2. Executive to whom payments are to be made.

                       Address for
Name                 Notices and Payments             Social Security No.
----                 --------------------             -------------------
Leo W. Ladehoff       4501 Troon Trail                  ###-##-####
                   Kettering, Ohio 45439

       3. PAYMENT OBLIGATION OF THE COMPANY TO EXECUTIVE
          UNDER THE EMPLOYMENT AGREEMENT.

Name                         Payment Obligation
----                         ------------------

Leo W. Ladehoff     Seven Thousand Dollars ($7,000) on the first day of each
                    month for a period of 120 consecutive months, commencing on
                    the later of (i) March 1, 1991 and (ii) the first day of the
                    month following the month in which Mr. Ladehoff ceases being
                    employed by the Company.



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