<PAGE>

                                  EXHIBIT 10.2

NEITHER THIS NOTE (AS DEFINED BELOW) NOR ANY INTEREST HEREIN MAY BE SOLD,
DISTRIBUTED, ASSIGNED, OFFERED, PLEDGED OR OTHERWISE TRANSFERRED WITHOUT THE
PRIOR WRITTEN CONSENT OF THE MAKER REPRESENTATIVE (AS HEREINAFTER DEFINED),
WHICH CONSENT MAY BE WITHHELD IN THE SOLE DISCRETION OF THE MAKER
REPRESENTATIVE.

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
OR APPLICABLE STATE SECURITIES LAWS. WITHOUT IN ANY WAY LIMITING THE TERMS OF
THE FOREGOING PARAGRAPH, NO INTEREST IN THIS NOTE MAY BE SOLD, DISTRIBUTED,
ASSIGNED, OFFERED, PLEDGED OR OTHERWISE TRANSFERRED UNLESS (A) THE MAKER
REPRESENTATIVE RECEIVES AN OPINION OF LEGAL COUNSEL FOR THE HOLDER OF THIS NOTE
SATISFACTORY TO THE MAKER REPRESENTATIVE STATING THAT SUCH TRANSACTION IS EXEMPT
FROM REGISTRATION OR (B) THE MAKER REPRESENTATIVE OTHERWISE SATISFIES ITSELF
THAT SUCH TRANSACTION IS EXEMPT FROM REGISTRATION.

UNDER CERTAIN CIRCUMSTANCES MORE FULLY DESCRIBED IN SECTION 1(C) HEREOF, THE
PAYMENT OF THIS NOTE SHALL BE SUBORDINATE TO THE PRIOR PAYMENT IN FULL AND
SATISFACTION, IN CASH, OF CERTAIN "SENIOR FUNDED INDEBTEDNESS" (AS HEREINAFTER
DEFINED).

                    CONTINGENT NON-NEGOTIABLE PROMISSORY NOTE

$3,050,000,000.00                                                  June 20, 2006
                                                               Chicago, Illinois

     FOR VALUE RECEIVED, each of undersigned (collectively, the "Makers" and
each individually a "Maker") hereby jointly and severally promises and agrees to
pay to the United States Gypsum Asbestos Personal Injury Settlement Trust (the
"Holder") the principal amount of THREE BILLION FIFTY MILLION AND NO/100 DOLLARS
($3,050,000,000.00), together with interest on the unpaid principal sum from
(and including) the Trigger Date (as hereinafter defined) (such date being the
"Interest Accrual Commencement Date") until (but excluding) the date upon which
the principal hereof is paid in full, at a fixed per annum rate equal to the 90
day LIBO Rate for U.S. Dollars as of the Trigger Date (as set forth on the
Bloomberg Financial Markets system), plus .40%, as hereinafter provided, in each
case subject to the terms and conditions hereof, including the provisions of
Section 1(b). Interest hereunder shall be calculated on the basis of a 360-day
year consisting of twelve 30-day months. References in this Contingent
Non-Negotiable Promissory Note (this "Note") to the "Plan" mean that certain
Joint Plan of Reorganization of USG Corporation and the other Makers filed with
the United States Bankruptcy Court for the District of Delaware on April 5, 2006
(as amended from time to time), together with the exhibits and schedules
thereto. This Note is the "Contingent Payment Note" referred to in such Plan.

<PAGE>

1.   Payment Obligations.

     (a)  Principal and Interest. Subject to Section 1(b) and 1(c), the
          principal amount of this Note shall be payable in two installments of
          $1,900,000,000 and $1,150,000,000, respectively, payable on the
          thirtieth (30th) and the one hundred and eightieth (180th) day,
          respectively, after the later of (x) Trigger Date or (y) if the FAIR
          Act has been enacted and become law prior to the Trigger Date, the
          Final Order Date. Each such payment date is referred to herein as a
          "Scheduled Principal Payment Date." Subject to Section 1(b), interest
          on the unpaid principal amount of this Note shall begin to accrue on
          the Interest Accrual Commencement Date and all accrued and unpaid
          interest shall be due and payable on the final Scheduled Principal
          Payment Date. Payments of principal and interest shall be made in
          lawful money of the United States of America, by (i) check or (ii)
          wire transfer of immediately available funds to such bank account of
          the Holder as the Holder may designate from time to time by at least
          thirty (30) days' prior written notice to the Maker Representative.
          Any payment (excluding any prepayment) on or in respect of this Note
          shall be applied first to accrued but unpaid interest and then to the
          principal balance hereof. The unpaid principal may, at the option of
          the Makers, be prepaid, in whole or in part, at any time without
          premium or penalty, through the payment of an amount equal to 100% of
          the principal amount being prepaid, together with all accrued and
          unpaid interest on this Note to (but excluding) the date of the
          prepayment. Any such prepayment shall be applied to installments of
          principal in such order as the Maker Representative shall elect at the
          time of such prepayment. At such time as this Note is paid or prepaid
          in full, it shall be surrendered to the Maker Representative (or any
          of the other Makers) and cancelled and shall not be reissued. Anything
          in this Note to the contrary notwithstanding, any payment that is due
          on a date other than a Business Day (as hereinafter defined) shall be
          made on the next succeeding Business Day (and such extension of time
          shall not be included in the computation of interest). As used in this
          Note, the term "Business Day" means any day other than a Saturday, a
          Sunday or a day on which commercial banks in Chicago, Illinois are
          required or authorized by law to be closed.

     (b)  Condition Precedent. The obligations (including the payment
          obligations) under this Note shall be subject to the condition
          precedent (the "Condition Precedent") that the Fairness in Asbestos
          Injury Resolution Act of 2005 or any substantially similar legislation
          creating a national trust or similar fund (any such legislation,
          including the Fairness in Asbestos Injury Resolution Act of 2005,
          being referred to herein as the "FAIR Act") has not been enacted and
          made law on or before the date occurring ten days (excluding Sundays)
          after the final adjournment sine die of the 109th Congress of the
          United States of America (the "Trigger Date"); provided, however,
          that:

          (i)  if the FAIR Act is not enacted and made law on or before the
               Trigger Date, the obligations under this Note shall vest and the
               Makers shall satisfy this Note as set forth in Section 1(a)
               above;


                                       2

<PAGE>

          (ii) if the FAIR Act is enacted and made law on or before the Trigger
               Date, and is not subject to an action, cause of action, suit or
               other proceeding challenging the constitutionality of the FAIR
               Act (a "Challenge Proceeding") on or before sixty (60) days after
               the Trigger Date, the Condition Precedent shall not be satisfied,
               the obligations under this Note shall not vest, this Note will be
               fully cancelled and the Pledge Agreement (as hereinafter defined)
               shall automatically terminate and the Collateral (as hereinafter
               defined), liens and security interests that may be granted under
               the Pledge Agreement shall automatically be released and
               terminated (at no cost or expense to the Makers); and

          (iii) if the FAIR Act is enacted and made law on or before the Trigger
               Date, but is subject to a Challenge Proceeding as of sixty (60)
               days after the Trigger Date, the Condition Precedent shall not
               yet be satisfied and the obligations under this Note shall not
               yet vest, subject to the resolution of the Challenge Proceeding
               by a Final Order (as defined below) as follows:

               (A)  if the Challenge Proceeding is resolved by a Final Order
                    such that the FAIR Act is unconstitutional in its entirety
                    or as applied to debtors in proceedings under chapter 11
                    ("Chapter 11") of the United States Bankruptcy Code, 11
                    U.S.C. Section 101, et seq., as amended (the "Bankruptcy
                    Code"), whose plans of reorganization have not yet been
                    confirmed and become substantially consummated (i.e.,
                    debtors that are then similarly situated to the Makers as of
                    February 1, 2006 (in a Chapter 11 case with a plan of
                    reorganization that has not yet been confirmed)), so that
                    such debtors will not be subject to the FAIR Act, then: (1)
                    the Condition Precedent shall be deemed to be satisfied on
                    the date of such Final Order (the date of such Final Order,
                    being the "Final Order Date"); (2) within thirty (30) days
                    after the Final Order Date, the first installment of
                    $1,900,000,000 of principal shall be due and payable; and
                    (3) within one hundred and eighty (180) days after the Final
                    Order Date, the final installment of $1,150,000,000 of
                    principal, together with all unpaid interest accrued (at the
                    rate set forth in, and accrued in accordance with the
                    provisions of, Section 1(a)) since the Interest Accrual
                    Commencement Date shall be due and payable, in each case, as
                    described in Section 1(a); or

               (B)  if the Challenge Proceeding is resolved by a Final Order in
                    a manner other than as contemplated by the immediately
                    preceding clause (A), then the Condition Precedent shall not
                    be satisfied, the obligations under this Note shall not
                    vest, this Note will be fully cancelled and the Pledge
                    Agreement shall automatically terminate and the Collateral,
                    liens and security interests that may be granted under the
                    Pledge Agreement shall automatically be released and
                    terminated (at no cost or expense to the Makers).


                                       3

<PAGE>

          (iv) As used in this Note, a "Final Order" means an order or judgment
               of any court of competent jurisdiction that has not been
               reversed, stayed, modified or amended, and as to which the time
               to appeal or seek certiorari or move for a new trial, reargument
               or rehearing has expired, and no appeal or petition for
               certiorari or other proceedings for a new trial, reargument or
               rehearing has been timely taken, or as to which any appeal that
               has been taken or any petition for certiorari that has been filed
               timely has been withdrawn or resolved by the highest court to
               which the order or judgment was appealed or from which certiorari
               was sought or the new trial, reargument or rehearing shall have
               been denied or resulted in no modification of such order.

     (c)  Subordination Terms. Except as set forth in the penultimate sentence
          of this Section 1(c), upon any payment or distribution of assets of
          any Maker of any kind or character, whether in cash, property or
          securities, to creditors upon any total or partial liquidation,
          dissolution, winding-up, reorganization, assignment for the benefit of
          creditors or marshaling of assets of any Maker or in a bankruptcy,
          reorganization, insolvency, receivership or other similar proceeding
          relating to any Maker or its assets, whether voluntary or involuntary,
          all obligations and liabilities in respect of the Senior Funded
          Indebtedness (as defined below) (including interest after the
          commencement of any bankruptcy or other like proceeding at the rate
          specified in the applicable Senior Funded Indebtedness whether or not
          such interest is an allowed claim in any such proceeding) due or to
          become due shall first be paid in full in cash before any payment or
          distribution of any kind or character is made on account of any
          principal, interest or other obligations or liabilities under this
          Note. Upon any such dissolution, winding-up, liquidation,
          reorganization, receivership or similar proceeding, any payment or
          distribution of assets of any Maker of any kind or character, whether
          in cash, property or securities, to which the Holder would be
          entitled, except for the provisions hereof, shall be paid by the
          Makers or by any receiver, trustee in bankruptcy, liquidating trustee,
          agent or other person making such payment or distribution, or by the
          Holder if received by it, directly to the holders of the Senior Funded
          Indebtedness or their representatives for application to the payment
          of such Senior Funded Indebtedness remaining unpaid until all such
          Senior Funded Indebtness has been paid in full in cash. In the event
          that, notwithstanding the foregoing (but subject to the following
          sentence), any payment or distribution of assets of any Maker of any
          kind or character, whether in cash, property or securities, shall be
          received by the Holder when such payment or distribution is prohibited
          by this Section 1(c), such payment or distribution shall be held in
          trust for the benefit of, and shall be paid over or delivered to, the
          holders of Senior Funded Indebtedness or their respective
          representatives for application to the payment of Senior Funded
          Indebtedness remaining unpaid until all such Senior Funded
          Indebtedness has been paid in full in cash. Nothing in this Section
          1(c) shall be deemed to limit or impair the grant of security by the
          Parent (as defined below) to the Holder pursuant to the Pledge
          Agreement as more fully described in Section 1(d) below, or the
          exercise of the rights or remedies of the Holder with respect to the
          collateral (and the receipt and the use of the proceeds thereof)


                                       4

<PAGE>

          granted thereunder. As used in this Note, "Senior Funded Indebtedness"
          shall mean (i) the permitted Funded Indebtedness (as defined below)
          described in clauses (i) - (vii) of Section 2(b), unless the
          instrument creating or evidencing the same or pursuant to which the
          same is outstanding expressly provides that such Funded Indebtedness
          shall not be senior in right of payment to this Note and (ii) any
          other Funded Indebtedness of a Maker approved as being "Senior Funded
          Indebtedness" by the Holder hereof.

     (d)  USG Corporation (the "Parent") is entering into a Pledge Agreement
          Regarding Contingent Payment Note on the date hereof (the "Pledge
          Agreement") pursuant to which it has agreed under certain
          circumstances to secure the payment obligations of the Makers under
          this Note. The Pledge Agreement provides that, upon the demand
          therefor by the Holder to the Parent following the occurrence and
          during the continuance of an Event of Default (as hereinafter defined)
          pursuant to Section 3(a)(i), the Parent shall grant to the Holder a
          security interest in that number of shares of previously authorized
          but unissued common stock (other than treasury stock) of the Parent
          that would entitle the Holder to 51% of the aggregate voting power of
          all such outstanding common stock on a fully-diluted basis after
          giving effect to such pledge (the "Collateral").

2.   Certain Covenants. Each Maker hereby covenants and agrees that, from and
     after the date of this Note and until such time as this Note has been paid
     in full or, pursuant to Section 1(b), has been cancelled:

     (a)  Prohibition on Dividends and Repurchases. The Parent shall not (1) pay
          dividends or make any other distributions on account of its capital
          stock, other than dividends or distributions payable solely in capital
          stock of the Parent or its subsidiaries (it being acknowledged and
          agreed that nothing herein shall be deemed to limit or restrict the
          Parent's right to effect the Rights Offering or to perform its
          obligations under the Equity Commitment Agreement (each, as defined in
          the Plan) or to effect any stock splits, adjustments or similar
          transactions) or (2) purchase or redeem any of its capital stock, in
          each of the cases of clauses (1) and (2), in an amount in excess of
          $150,000,000, in aggregate.

     (b)  Permitted Funded Indebtedness. The aggregate amount of the Makers'
          Funded Indebtedness that is senior to this Note (through any
          combination of the granting of security and/or subordination), shall
          be limited to: (i) indebtedness incurred in connection with the
          Makers' exit from bankruptcy in a maximum principal amount not to
          exceed $750,000,000 at any time outstanding, (ii) amounts necessary to
          fund any Plan Distributions (as defined in the Plan), after taking
          account of available cash, including payments to the Holder (including
          payments on this Note and the Non-Contingent Note), payments to
          unsecured creditors and payments to holders of Asbestos Property
          Damage Claims (as defined in the Plan), (iii) amounts necessary to
          fund operations, working capital needs and capital expenditures of the
          Makers, (iv) financings of or for letters of credit (including
          facilities relating to Funded Indebtedness incurred to provide
          collateral for letters of credit and similar instruments, or so-called
          "synthetic letter of credit


                                       5

<PAGE>

          facilities"), bonding requirements, bankers' acceptances, bonds,
          capital leases, interest rate, currency or commodity swap agreements,
          cap agreements or collar agreements (and any other similar agreement
          or arrangement designed to protect a person against fluctuations in
          interest rates, currency exchange rates or commodity prices) or
          similar instruments entered into, issued or obtained in the ordinary
          course of the Makers' businesses, (v) other Funded Indebtedness in a
          maximum principal amount not to exceed $125,000,000 at any time
          outstanding, (vi) payment obligations hereunder and under the
          Non-Contingent Note and (vii) replacements, refinancings, renewals or
          extensions of any of the foregoing. In determining the principal
          amount of any Funded Indebtedness for purposes hereof where such
          Funded Indebtedness is limited in recourse to particular assets of the
          Makers, the amount of such Funded Indebtedness thereunder shall be
          deemed limited to the value of such assets (to the extent less than
          the aggregate amount of such Funded Indebtedness).

     (c)  As used herein, "Funded Indebtedness" means, with respect to any
          Maker:

          (i)  indebtedness of such Maker for borrowed money;

          (ii) obligations of such Maker evidenced by debentures, promissory
               notes or other similar instruments;

          (iii) obligations of such Maker in respect of letters of credit,
               bankers' acceptances or other similar instruments, excluding
               obligations in respect of trade letters of credit, bankers'
               acceptances or other similar instruments issued in respect of
               trade payables or similar obligations;

          (iv) obligations of such Maker to pay the deferred and unpaid purchase
               price of property or services which are recorded as liabilities
               in accordance with Generally Accepted Accounting Principles as in
               effect from time to time in the United States ("GAAP"), excluding
               trade payables, advances on contracts, deferred compensation and
               similar liabilities arising in the ordinary course of business of
               such Maker;

          (v)  rent obligations of such Maker as lessee under any lease
               arrangement classified as a capital lease on the balance sheet of
               such Maker in accordance with GAAP;

          (vi) obligations of such Maker under any interest rate, currency or
               commodity swap agreement, cap agreement or collar agreement or
               other similar arrangement or agreement designed to protect such
               Maker against fluctuations in interest rates, currency exchange
               rates or commodity prices; and

          (vii) guaranties, surety arrangements and similar arrangements of or
               with respect to any Funded Indebtedness of any other person or
               entity.


                                       6

<PAGE>

3.   Events of Default and Remedies.

     (a)  Events of Default. So long as this Note has not been paid in full,
          each of the following events will constitute an "Event of Default":

          (i)  any default in the payment of the principal or accrued interest
               payable under this Note as and when the same shall become due and
               payable;

          (ii) any breach of any of the covenants contained in Section 2, and
               continuance of such breach for a period of thirty (30) days after
               the Maker Representative's receipt of a Default Notice from the
               Holder with respect to such breach;

          (iii) commencement of an involuntary case or other proceeding against
               any Maker seeking (A) liquidation, reorganization or other relief
               with respect to it or its debts under any applicable bankruptcy,
               insolvency or other similar law now or hereafter in effect, (B)
               the appointment of a receiver, liquidator, custodian or trustee
               of any Maker or for all or substantially all the property and
               other assets of any Maker or (C) the winding up or liquidation of
               the affairs of any Maker, if, in the case of any of (A), (B) or
               (C) above, such case or proceeding shall remain unstayed and
               undismissed for a period of sixty (60) days; or

          (iv) (A) commencement of a voluntary case by any Maker under any
               applicable bankruptcy, insolvency or other similar law now or
               hereafter in effect, (B) consent by any Maker to the entry of an
               order for relief in an involuntary case against such Maker under
               any such law, (C) consent by any Maker to the appointment or
               taking possession by a receiver, liquidator, custodian or trustee
               of such Maker or for all or substantially all its assets or (D) a
               general assignment by any Maker for the benefit of its creditors.

     (b)  Remedies. If an Event of Default specified in Section 3(a)(i) or (ii)
          shall occur, then the Holder may, by written notice to the Maker
          Representative (a "Default Notice"), so long as the Event of Default
          is continuing, declare all unpaid principal and accrued and unpaid
          interest under this Note immediately due and payable without further
          presentment, demand, protest or further notice, all of which are
          hereby expressly waived by the Makers. If any Event of Default
          specified in Section 3(a)(iii) or (iv) shall occur, then, without any
          notice to the Makers or any other act by the Holder, the entire
          principal amount of this Note (together with all accrued interest
          thereon) shall become immediately due and payable without presentment,
          demand, protest or other notice of any kind, all of which are hereby
          expressly waived by the Makers. Notwithstanding the foregoing, in the
          event that following the occurrence of an Event of Default hereunder
          and the acceleration of the payments due hereunder, any such payments
          received by the Holder hereof on account of this Note shall be deemed
          received and held in trust for the benefit of the Holder and the
          Makers until applied as


                                       7

<PAGE>

          follows: (x) upon and after the satisfaction of the Condition
          Precedent and the vesting of the obligations and liabilities hereunder
          pursuant to Section 1(b), such amounts may turned over to and be
          applied by the Holder to the obligations and liabilities then due and
          owing hereunder or (y) upon the occurrence of any event of the type
          described in Section 1(b)(ii) or 1(b)(iii)(B) and the cancellation of
          this Note, all such amounts shall be deemed the property of, and shall
          be promptly thereafter be returned to, the Maker.

4.   Waivers; Amendments. Except as set forth in Sections 3(a)(i), 3(a)(ii) and
     3(b), to the extent permitted by applicable law, each Maker hereby
     expressly waives demand for payment, presentment, notice of dishonor,
     notice of intent to demand, notice of acceleration, notice of intent to
     accelerate, protest, notice of protest and diligence in collecting and the
     bringing of suit against any such Maker with respect to this Note. Each
     Maker agrees that the Holder may extend the time for repayment or accept
     partial payment an unlimited number of times without discharging or
     releasing any of the Makers from their respective obligations (including
     the obligations) under this Note. No delay or omission on the part of the
     Holder in exercising any power or right in connection herewith shall
     operate as a waiver of such right or any other right under this Note, nor
     shall any single or partial exercise of any such right or power or any
     abandonment or discontinuance of steps to enforce such a right or power,
     preclude any other or further exercise thereof or the exercise of any other
     right or power. No amendment, modification or waiver of any provision of
     this Note, nor any consent to any departure therefrom, shall in any event
     be effective unless the same shall be in writing and signed by the person
     (or such person's attorney-in-fact) against whom enforcement thereof is to
     be sought, and then such waiver or consent shall be effective only in the
     specific instance and for the specific purpose for which given.

5.   No Recourse Against Individuals. No director, officer, employee, manager,
     shareholder, member, partner or representative of any of the Makers (in
     each case, in such person's capacity as such) shall have any personal
     liability in respect of any obligations (including the payment obligations)
     of the Makers under this Note, or for any claim based on, with respect to
     or by reason of such obligations or their creation, by reason of his/her or
     its status as such. By accepting this Note, the Holder hereby waives and
     releases all such liability. Such waiver and release is part of the
     consideration for the issue of the Note by the Makers.

6.   Joint and Several Liability; Limitations.

     (a)  Subject to the terms and conditions of this Note, all payment
          obligations of the Makers hereunder shall be joint and several.

     (b)  Notwithstanding any provisions of this Note to the contrary, it is
          intended that the joint and several nature of the payment obligations
          of the Makers hereunder not constitute a "Fraudulent Conveyance" (as
          hereinafter defined). Consequently, the Holder hereby agrees that if
          the payment obligations of a Maker would, but for the application of
          this sentence, constitute a Fraudulent Conveyance, the payment
          obligations of such Maker shall be valid and enforceable only to the
          maximum


                                       8

<PAGE>

          extent that would not cause such payment obligations to constitute a
          Fraudulent Conveyance, and the payment obligations of such Maker and
          this Note shall automatically be deemed to have been amended
          accordingly. For purposes hereof, "Fraudulent Conveyance" means a
          fraudulent conveyance or fraudulent transfer under the applicable
          provisions of any fraudulent conveyance or fraudulent transfer law or
          similar law of any state, nation or other governmental unit, as in
          effect from time to time, including, without limitation, the
          Bankruptcy Code.

     (c)  The Makers shall not exercise any rights which they may acquire by way
          of subrogation to the rights of the Holder or any rights of
          contribution or indemnity from any other Maker, in each case,
          hereunder until all of the payment obligations of the Makers under
          this Note shall have been paid in full.

7.   Certain Representations. Each Maker hereby represents, solely as to itself,
     that: (a) such Maker is duly incorporated, validly existing and in good
     standing under the laws of its organization and has full corporate power
     and authority to execute and deliver this Note; (b) such Maker's execution
     and delivery of this Note has been duly authorized by all necessary
     corporate action on its part; and (c) this Note constitutes a legal, valid
     and binding obligation of such Maker, enforceable against such Maker in
     accordance with the terms hereof, except as such enforceability may be
     limited by: (i) bankruptcy, insolvency, reorganization, fraudulent transfer
     or conveyance and other laws of general applicability relating to or
     affecting creditors' rights and (ii) general principles of equity
     (regardless of whether such enforceability is considered in a proceeding in
     equity or at law).

8.   Prohibition on Assignment. Neither this Note nor any interest herein may be
     sold, distributed, assigned, offered, pledged or otherwise transferred
     without the prior written consent of the Maker Representative, which
     consent may be withheld in the sole discretion of the Maker Representative.
     The Holder understands that none of this Note, the Pledge Agreement or the
     Collateral have been registered, and in no event shall the Makers be
     required to register any of the foregoing, under the Securities Act of
     1933, as amended (the "Securities Act") or any state securities laws. As
     such, without limiting the provisions of the first sentence of this Section
     8 in any way, any sale, distribution, assignment, offering, pledge or other
     transfer of this Note may only be effected in a transaction that is exempt
     from registration under the Securities Act and applicable state securities
     laws, as evidenced by a legal opinion from legal counsel to the Holder,
     which, in each of the case of such legal opinion and legal counsel, are
     reasonably acceptable to the Maker Representative.

9.   Entire Agreement. This Note, the Pledge Agreement and the Plan constitute
     the entire agreement and understanding among the Holder and the Makers with
     respect to the subject matter of this Note and supersede all prior
     agreements and understandings, oral or written, among or binding upon such
     parties with respect to the subject matter of this Note.


                                       9

<PAGE>

10.  Appointment of Maker Representative; Notices.

     (a)  Each Maker hereby designates the Parent as its representative, agent
          and attorney-in-fact to act as specified herein for and on behalf of
          such Maker (in such capacity, the "Maker Representative"). Each Maker
          hereby authorizes the Maker Representative to take such actions on its
          behalf under the terms of this Note and the Pledge Agreement and to
          exercise such powers and perform such duties hereunder and thereunder
          as are specified in such agreements or are reasonably incidental
          thereto, including the giving and receiving of all notices, consents,
          acquittances and agreements and taking all other actions (including in
          respect of compliance with covenants), in each case, on behalf of the
          Makers under this Note and the Pledge Agreement. The Maker
          Representative hereby accepts such appointment. The Holder shall be
          entitled to rely on all notices, requests, consents, certifications
          and/or authorizations or other similar acts delivered or taken by the
          Maker Representative for or on behalf of any Maker pursuant hereto or
          the Pledge Agreement without inquiry, as if such notices, requests,
          consents, certifications and/or authorizations or other similar acts
          were delivered or taken directly by any such Maker. Each agreement,
          undertaking, notice or consent made or given on behalf of a Maker by
          the Maker Representative shall be deemed for all purposes to have been
          made or given by such Maker and shall be binding upon and enforceable
          against such Maker to the same extent as it if the same had been made
          directly by such Maker.

     (b)  All notices and communications provided for hereunder shall be in
          writing and sent (a) by facsimile if the sender on the same day sends
          a confirming copy of such notice by a recognized overnight-delivery
          service (charges prepaid), (b) by registered or certified mail with
          return receipt requested (postage prepaid) or (c) by a recognized
          overnight-delivery service (with charges prepaid). Any such notice
          shall be sent:

          (i)  if to the Holder, at such address as the Holder shall have
               specified to the Makers in writing; or

          (ii) if to any Maker, to the Maker Representative, c/o USG
               Corporation, 125 South Franklin Street, Chicago, Illinois 60606,
               Attention: Corporate Secretary, or to such other address as the
               Maker Representative may hereafter specify for itself to the
               Holder in writing; with a copy to Jones Day, 77 West Wacker
               Drive, Chicago, Illinois 60601, Attention: Brad B. Erens, or to
               such other address as Jones Day shall have specified to the
               Holder in writing.

11.  Captions; Interpretation. The captions and section headings appearing
     herein are included solely for convenience of reference and are not
     intended to affect the interpretation of any provision of this Note. Except
     where the context otherwise requires, the defined terms used in this Note
     shall apply equally to the singular and plural forms of the terms defined.
     Whenever the context may require, any pronoun shall include the
     corresponding masculine, feminine and neuter forms. The words "include,"
     "includes"


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<PAGE>

     and "including" shall be deemed to be followed by the phrase "without
     limitation." The word "will" shall be construed to have the same meaning
     and effect as the word "shall" and both "will" and "shall" are used in the
     mandatory and imperative sense. The word "may" means is authorized or
     permitted to, while "may not" means is not authorized or permitted to.
     Unless the context otherwise requires: (i) any definition of or reference
     to any agreement or other document herein shall be construed as referring
     to such agreement or other document as from time to time amended, restated,
     supplemented or otherwise modified (subject to any restrictions on such
     amendments, restatements, supplements or modifications set forth herein or
     therein); (ii) any reference herein to the subsidiaries of any entity shall
     be construed to include such entity's direct and indirect subsidiaries;
     (iii) the words "herein," "hereof," and "hereunder," and words of similar
     import, shall be construed to refer to this Agreement in its entirety and
     not to any particular provision hereof; and (iv) all references herein to
     sections shall be construed to refer to sections of this Note.

12.  Severability. If any provision contained in this Note shall for any reason
     be held to be invalid, illegal or unenforceable in any respect, that
     provision will, to the extent possible, be modified in such manner as to be
     valid, legal and enforceable but so as to most nearly retain the intent of
     the parties hereto as expressed herein, and if such a modification is not
     possible, that provision will be severed from this Note, and in either case
     the validity, legality and enforceability of the remaining provisions of
     this Note will not in any way be affected or impaired thereby.

13.  GOVERNING LAW. THE CONSTRUCTION, VALIDITY AND ENFORCEABILITY OF THIS NOTE
     SHALL BE GOVERNED BY THE SUBSTANTIVE LAWS OF THE STATE OF DELAWARE, WITHOUT
     GIVING EFFECT TO ANY PRINCIPLES OF CONFLICTS OF LAWS THEREOF THAT WOULD
     RESULT IN THE APPLICATION OF THE LAWS OF ANY OTHER JURISDICTION.

                                      * * *


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<PAGE>

                                         MAKERS:

                                         USG CORPORATION
                                         UNITED STATES GYPSUM COMPANY
                                         USG INTERIORS, INC.
                                         USG INTERIORS INTERNATIONAL, INC.
                                         L&W SUPPLY CORPORATION
                                         BEADEX MANUFACTURING, LLC
                                         B-R PIPELINE COMPANY
                                         LA MIRADA PRODUCTS CO., INC.
                                         USG INDUSTRIES, INC.
                                         USG PIPELINE COMPANY
                                         STOCKING SPECIALISTS, INC.


                                         By: /s/ Richard H. Fleming
                                             -----------------------------------
                                         Name: Richard H. Fleming
                                         Title: In the capacity listed on
                                                Schedule I hereto with respect
                                                to each entity listed above

                 [Signature Page to Contingent Promissory Note]

<PAGE>

                                   Schedule I

                        Capacities of Richard H. Fleming

<TABLE>
<CAPTION>
            MAKER                               CAPACITY
            -----                               --------
<S>                                 <C>
USG CORPORATION                     EXECUTIVE VICE PRESIDENT AND
                                    CHIEF FINANCIAL OFFICER
UNITED STATES GYPSUM COMPANY        VICE PRESIDENT AND ASST. TREASURER
USG INTERIORS, INC.                 VICE PRESIDENT AND ASST. TREASURER
USG INTERIORS INTERNATIONAL, INC.   VICE PRESIDENT
L&W SUPPLY CORPORATION              VICE PRESIDENT AND ASST. TREASURER
BEADEX MANUFACTURING, LLC           VICE PRESIDENT
B-R PIPELINE COMPANY                VICE PRESIDENT
LA MIRADA PRODUCTS CO., INC.        VICE PRESIDENT
USG INDUSTRIES, INC.                VICE PRESIDENT
USG PIPELINE COMPANY                VICE PRESIDENT
STOCKING SPECIALISTS, INC.          VICE PRESIDENT
</TABLE>


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