<PAGE>
 
                                                                   EXHIBIT 10(a)
                                                                   -------------

                                   AGREEMENT
                                      AND
                             PLAN OF REORGANIZATION



     AGREEMENT AND PLAN OF REORGANIZATION (the "Agreement") entered into as of
the 16th day of September, 1996, by and between CENTRAL BANCORPORATION, INC.
    ----
("Central"), a Texas corporation, and NORWEST CORPORATION ("Norwest"), a
Delaware corporation.

     WHEREAS, the parties hereto desire to effect a reorganization whereby a
wholly-owned subsidiary of Norwest will merge with and into Central (the
"Merger") pursuant to an agreement and plan of merger (the "Merger Agreement")
in substantially the form attached hereto as Exhibit A, which provides, among
other things, for the conversion and exchange of the shares of Common Stock of
Central of the par value of $2.50 per share ("Central Common Stock") outstanding
immediately prior to the time the Merger becomes effective in accordance with
the provisions of the Merger Agreement into shares of voting Common Stock of
Norwest of the par value of $1-2/3 per share ("Norwest Common Stock"),

     NOW, THEREFORE, to effect such reorganization and in consideration of the
premises and the mutual covenants and agreements contained herein, the parties
hereto do hereby represent, warrant, covenant and agree as follows:

     1.  BASIC PLAN OF REORGANIZATION

     (a)  Merger.  Subject to the terms and conditions contained herein a
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wholly-owned subsidiary of Norwest (the "Merger Co.") will be merged by
statutory merger with and into Central pursuant to the Merger Agreement, with
Central as the surviving corporation, in which merger each share of Central
Common Stock outstanding immediately prior to the Effective Time of the Merger
(as defined below) (other than shares as to which statutory dissenters'
appraisal rights have been exercised) will be converted into and exchanged for
the number of shares of Norwest Common Stock equal to the Norwest Share Amount
(as defined below).  The "Norwest Share Amount" shall be an amount determined by
(A) dividing 4,700,000 by (B) the sum of (i) the number of shares of Central
Common Stock outstanding immediately prior to the Effective Time of the Merger,
plus (ii) the number of shares of Central Common Stock issuable pursuant to the
exercise of Central Options (as defined below) or other rights to acquire
Central Common Stock outstanding immediately prior to the Effective Time of the
Merger.

     (b)  Norwest Common Stock Adjustments.  If, between the date hereof and the
          --------------------------------                                      
Effective Time of the Merger, shares of Norwest Common Stock shall be changed
into a different number of shares or a different class of shares by reason of
any reclassification,

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<PAGE>
 
recapitalization, split-up, combination, exchange of shares or readjustment, or
if a stock dividend thereon shall be declared with a record date within such
period (a "Common Stock Adjustment"), then the number of shares of Norwest
Common Stock into which a share of Central Common Stock shall be converted
pursuant to subparagraph (a), above, will be appropriately and proportionately
adjusted so that the number of such shares of Norwest Common Stock into which a
share of Central Common Stock shall be converted will equal the number of shares
of Norwest Common Stock which holders of shares of Central Common Stock would
have received pursuant to such Common Stock Adjustment had the record date
therefor been immediately following the Effective Time of the Merger.

     (c)  Fractional Shares.  No fractional shares of Norwest Common Stock and
          -----------------                                                   
no certificates or scrip certificates therefor shall be issued to represent any
such fractional interest, and any holder thereof shall be paid an amount of cash
equal to the product obtained by multiplying the fractional share interest to
which such holder is entitled by the average of the closing prices of a share of
Norwest Common Stock as reported by the consolidated tape of the New York Stock
Exchange for each of the five (5) trading days ending on the day immediately
preceding the meeting of shareholders required by paragraph 4(c) of this
Agreement.

     (d)  Mechanics of Closing Merger.  Subject to the terms and conditions set
          ---------------------------                                          
forth herein, the Merger Agreement shall be executed and it or Articles of
Merger or a Certificate of Merger shall be filed with the Secretary of State of
the State of Texas within ten (10) business days following the satisfaction or
waiver of all conditions precedent set forth in Sections 6 and 7 of this
Agreement or on such other date as may be agreed to by the parties (the "Closing
Date").  Each of the parties agrees to use its best efforts to cause the Merger
to be completed as soon as practicable after the receipt of final regulatory
approval of the Merger and the expiration of all required waiting periods.  The
time that the filing referred to in the first sentence of this paragraph is made
is herein referred to as the "Time of Filing".  The day on which such filing is
made and accepted is herein referred to as the "Effective Date of the Merger".
The "Effective Time of the Merger" shall be 11:59 p.m. Fort Worth, Texas time on
the Effective Date of the Merger.  At the Effective Time of the Merger on the
Effective Date of the Merger, the separate existence of Merger Co. shall cease
and Merger Co. will be merged with and into Central pursuant to the Merger
Agreement.

     The closing of the transactions contemplated by this Agreement and the
Merger Agreement (the "Closing") shall take place on the Closing Date at the
offices of Norwest, Norwest Center, Sixth and Marquette, Minneapolis, Minnesota.

     2.  REPRESENTATIONS AND WARRANTIES OF CENTRAL.  Central represents and
warrants to Norwest as follows:

     (a)  Organization and Authority.  Central is a corporation duly organized,
          --------------------------                                           
validly existing and in good standing under the laws of the State of Texas, is
duly qualified to do business and is in good standing in all jurisdictions where
its ownership or leasing of

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property or the conduct of its business requires it to be so qualified and
failure to be so qualified would have a material adverse effect on Central and
the Central Subsidiaries taken as a whole and has corporate power and authority
to own its properties and assets and to carry on its business as it is now being
conducted. Central is registered as a bank holding company with the Federal
Reserve Board under the Bank Holding Company Act of 1956, as amended (the "BHC
Act"). Central has furnished Norwest true and correct copies of its articles of
incorporation and by-laws, as amended.

     (b)  Central's Subsidiaries.  Schedule 2(b) sets forth a complete and
          ----------------------                                          
correct list of all of Central's subsidiaries as of the date hereof
(individually a "Central Subsidiary" and collectively the "Central
Subsidiaries"), all shares of the outstanding capital stock of each of which,
except as set forth on Schedule 2(b), are owned directly or indirectly by
Central.  No equity security of any Central Subsidiary is or may be required to
be issued by reason of any option, warrant, scrip, preemptive right, right to
subscribe to, call or commitment of any character whatsoever relating to, or
security or right convertible into, shares of any capital stock of such
subsidiary, and there are no contracts, commitments, understandings or
arrangements by which any Central Subsidiary is bound to issue additional shares
of its capital stock, or any option, warrant or right to purchase or acquire any
additional shares of its capital stock.  Subject to the Texas Business
Corporation Act, all of such shares so owned by Central are fully paid and
nonassessable and are owned by it free and clear of any lien, claim, charge,
option, encumbrance or agreement with respect thereto.  Each Central Subsidiary
is a corporation duly organized, validly existing, duly qualified to do business
and in good standing under the laws of its jurisdiction of incorporation, and
has corporate power and authority to own or lease its properties and assets and
to carry on its business as it is now being conducted.  Except as set forth on
Schedule 2(b), Central does not own beneficially, directly or indirectly, more
than 5% of any class of equity securities or similar interests of any
corporation, bank, business trust, association or similar organization, and is
not, directly or indirectly, a partner in any partnership or party to any joint
venture.

     (c)  Capitalization.  The authorized capital stock of Central consists of
          --------------                                                      
5,000,000 shares of common stock, $2.50 par value, of which as of the close of
business on June 30, 1996, 2,623,377 shares were outstanding and no shares were
held in the treasury. As of the date hereof, there are outstanding options
(each, a "Central Option") to purchase an aggregate of 25,260 shares of Central
Common Stock under the 1988 Incentive Stock Option Plan of Texas Security
Bancshares, Inc. The maximum number of shares of Central Common Stock (assuming
for this purpose that phantom shares and other share-equivalents constitute
Central Common Stock) that would be outstanding as of the Effective Date of the
Merger if all options, warrants, conversion rights and other rights with respect
thereto were exercised is 2,648,637. All of the outstanding shares of capital
stock of Central have been duly and validly authorized and issued and are fully
paid and nonassessable. Except as set forth in Schedule 2(c), there are no
outstanding subscriptions, contracts, conversion privileges, options, warrants,
calls, preemptive rights or other rights obligating Central or any Central
Subsidiary to issue, sell or otherwise dispose of, or to purchase, redeem or
otherwise acquire, any shares of capital stock of

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Central or any Central Subsidiary. Since June 30, 1996 no shares of Central
capital stock have been purchased, redeemed or otherwise acquired, directly or
indirectly, by Central or any Central Subsidiary and, except as set forth on
Schedule 2(c), no dividends or other distributions have been declared, set
aside, made or paid to the shareholders of Central.

     (d)  Authorization.  Central has the corporate power and authority to enter
          -------------                                                         
into this Agreement and the Merger Agreement and, subject to any required
approvals of its shareholders, to carry out its obligations hereunder and
thereunder.  The execution, delivery and performance of this Agreement and the
Merger Agreement by Central and the consummation of the transactions
contemplated hereby and thereby have been duly authorized by the Board of
Directors of Central.  Subject to such approvals of shareholders and of
government agencies and other governing boards having regulatory authority over
Central as may be required by statute or regulation, this Agreement and the
Merger Agreement are valid and binding obligations of Central enforceable
against Central in accordance with their respective terms.

     Except as set forth on Schedule 2(d), neither the execution, delivery and
performance by Central of this Agreement or the Merger Agreement, nor the
consummation of the transactions contemplated hereby and thereby, nor compliance
by Central with any of the provisions hereof or thereof, will (i) violate,
conflict with, or result in a breach of any provision of, or constitute a
default (or an event which, with notice or lapse of time or both, would
constitute a default) under, or result in the termination of, or accelerate the
performance required by, or result in a right of termination or acceleration of,
or result in the creation of, any lien, security interest, charge or encumbrance
upon any of the properties or assets of Central or any Central Subsidiary under
any of the terms, conditions or provisions of (x) its articles of incorporation
or by-laws or (y) any material note, bond, mortgage, indenture, deed of trust,
license, lease, agreement or other instrument or obligation to which Central or
any Central Subsidiary is a party or by which it may be bound, or to which
Central or any Central Subsidiary or any of the properties or assets of Central
or any Central Subsidiary may be subject, or (ii) subject to compliance with the
statutes and regulations referred to in the next paragraph, to the best
knowledge of Central, violate any judgment, ruling, order, writ, injunction,
decree, statute, rule or regulation applicable to Central or any Central
Subsidiary or any of their respective properties or assets.

     Other than in connection or in compliance with the provisions of the
Securities Act of 1933 and the rules and regulations thereunder (the "Securities
Act"), the Securities Exchange Act of 1934 and the rules and regulations
thereunder (the "Exchange Act"), the securities or blue sky laws of the various
states or filings, consents, reviews, authorizations, approvals or exemptions
required under the BHC Act or the Hart-Scott-Rodino Antitrust Improvements Act
of 1976 ("HSR Act"), and filings required to effect the Merger under Texas law,
no notice to, filing with, exemption or review by, or authorization, consent or
approval of, any public body or authority is necessary for the consummation by
Central of the transactions contemplated by this Agreement and the Merger
Agreement.

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<PAGE>
 
     (e)  Central Financial Statements.  The consolidated balance sheets of
          ----------------------------                                     
Central and Central's Subsidiaries as of December 31, 1995 and 1994 and related
consolidated statements of income, shareholders' equity and cash flows for the
three years ended December 31, 1995, together with the notes thereto, certified
by KMPG Peat Marwick LLP and included in Central's Annual Report on Form 10-K
for the fiscal year ended December 31, 1995 (the "Central 10-K") as filed with
the Securities and Exchange Commission (the "SEC"), and the unaudited
consolidated statements of financial condition of Central and Central's
Subsidiaries as of June 30, 1996 and the related unaudited consolidated
statements of income, shareholders' equity and cash flows for the six (6) months
then ended included in Central's Quarterly Report on Form 10-Q for the fiscal
quarter ended June 30, 1996 as filed with the SEC (collectively, the "Central
Financial Statements"), have been prepared in accordance with generally accepted
accounting principles applied on a consistent basis and present fairly (subject,
in the case of financial statements for interim periods, to normal recurring
adjustments) the consolidated financial position of Central and Central's
Subsidiaries at the dates and the consolidated results of operations and cash
flows of Central and Central's Subsidiaries for the periods stated therein.

     (f)  Reports.  Since December 31, 1990, Central and each Central Subsidiary
          -------                                                               
has filed all reports, registrations and statements, together with any required
amendments thereto, that it was required to file, if any, with (i) the SEC,
including, but not limited to, Forms 10-K, Forms 10-Q and proxy statements, (ii)
the Federal Reserve Board, (iii) the Federal Deposit Insurance Corporation (the
"FDIC"), (iv) the United States Comptroller of the Currency (the "Comptroller")
and (v) any applicable state securities or banking authorities.  All such
reports and statements filed with any such regulatory body or authority are
collectively referred to herein as the "Central Reports".  As of their
respective dates, the Central Reports complied in all material respects with all
the rules and regulations promulgated by the SEC, the Federal Reserve Board, the
FDIC, the Comptroller and applicable state securities or banking authorities, as
the case may be, and did not contain any untrue statement of a material fact or
omit to state a material fact required to be stated therein or necessary in
order to make the statements therein, in light of the circumstances under which
they were made, not misleading.  Copies of all the Central Reports have been
made available to Norwest by Central.

     (g)  Properties and Leases.  Except as may be reflected in the Central
          ---------------------                                            
Financial Statements and except for any lien for current taxes not yet
delinquent, Central and each Central Subsidiary have good title free and clear
of any material liens, claims, charges, options, encumbrances or similar
restrictions to all the real and personal property reflected in Central's
consolidated balance sheet as of June 30, 1996 included in Central's Quarterly
Report on Form 10-Q, and all real and personal property acquired since such
date, except such real and personal property as has been disposed of in the
ordinary course of business.  All leases of real property and all other leases
material to Central or any Central Subsidiary pursuant to which Central or such
Central Subsidiary, as lessee, leases real or personal property, which leases
are described on Schedule 2(g), are valid and effective in 

                                       5
<PAGE>
 
accordance with their respective terms, and there is not, under any such lease,
any material existing default by Central or such Central Subsidiary or any event
which, with notice or lapse of time or both, would constitute such a material
default. Substantially all Central's and each Central Subsidiary's buildings and
equipment in regular use have been well maintained and are in good and
serviceable condition, reasonable wear and tear excepted.

     (h)  Taxes.  Each of Central and the Central Subsidiaries has filed all
          -----                                                             
federal, state, county, local and foreign tax returns, including information
returns, required to be filed by it, and paid all taxes owed by it, including
those with respect to income, withholding, social security, unemployment,
workers compensation, franchise, ad valorem, premium, excise and sales taxes,
and no taxes shown on such returns to be owed by it or assessments received by
it are delinquent.  The federal income tax returns of Central and the Central
Subsidiaries for the fiscal year ended December 31, [1992] and for all fiscal
years prior thereto, are for the purposes of routine audit by the Internal
Revenue Service closed because of the statute of limitations, and no claims for
additional taxes for such fiscal years are pending.  Except only as set forth on
Schedule 2(h), (i) neither Central nor any Central Subsidiary is a party to any
pending action or proceeding, nor is any such action or proceeding threatened by
any governmental authority, for the assessment or collection of taxes, interest,
penalties, assessments or deficiencies and (ii) no issue has been raised by any
federal, state, local or foreign taxing authority in connection with an audit or
examination of the tax returns, business or properties of Central or any Central
Subsidiary which has not been settled, resolved and fully satisfied.  Each of
Central and the Central Subsidiaries has paid all taxes owed or which it is
required to withhold from amounts owing to employees, creditors or other third
parties.  The consolidated balance sheet as of June 30, 1996, referred to in
paragraph 2(e) hereof, includes adequate provision for all accrued but unpaid
federal, state, county, local and foreign taxes, interest, penalties,
assessments or deficiencies of Central and the Central Subsidiaries with respect
to all periods through the date thereof.

     (i)  Absence of Certain Changes.  Since December 31, 1995 there has been no
          --------------------------                                            
change in the business, financial condition or results of operations of Central
or any Central Subsidiary, which has had, or may reasonably be expected to have,
a material adverse effect on the business, financial condition or results of
operations of Central and the Central Subsidiaries taken as a whole (other than
changes in banking laws or regulations, or interpretations thereof, that affect
the banking industry generally or changes in the general level of interest
rates).

     (j)  Commitments and Contracts.  Except as set forth on Schedule 2(j),
          -------------------------                                        
neither Central nor any Central Subsidiary is a party or subject to any of the
following (whether written or oral, express or implied):

          (i)  any employment contract or understanding (including any
     understandings or obligations with respect to severance or termination pay
     liabilities or fringe benefits) with any present or former officer,
     director, employee

                                       6
<PAGE>
 
     or consultant (other than those which are terminable at will by Central or
     such Central Subsidiary);

          (ii)  any plan, contract or understanding providing for any bonus,
     pension, option, deferred compensation, retirement payment, profit sharing
     or similar arrangement with respect to any present or former officer,
     director, employee or consultant;

          (iii) any labor contract or agreement with any labor union;

          (iv)  any contract not made in the ordinary course of business
     containing covenants which limit the ability of Central or any Central
     Subsidiary to compete in any line of business or with any person or which
     involve any restriction of the geographical area in which, or method by
     which, Central or any Central Subsidiary may carry on its business (other
     than as may be required by law or applicable regulatory authorities);

          (v)   any other contract or agreement which is a "material contract"
     within the meaning of Item 601(b)(10) of Regulation S-K; or

          (vi)  any lease with annual rental payments aggregating $10,000 or
     more; or

          (vii)  any agreement or commitment with respect to the Community
     Reinvestment Act with any state or federal bank regulatory authority or any
     other party; or

          (viii) any current or past agreement, contract or understanding with
     any current or former director, officer, employee, consultant, financial
     adviser, broker, dealer, or agent providing for any rights of
     indemnification in favor of such person or entity.

     (k)  Litigation and Other Proceedings.  Central has furnished Norwest
          --------------------------------                                
copies of (i) all attorney responses to the request of the independent auditors
for Central with respect to loss contingencies as of December 31, 1995 in
connection with the Central financial statements included in the Central 10-K,
and (ii) a written list of legal and regulatory proceedings filed against
Central or any Central Subsidiary since said date.  Neither Central nor any
Central Subsidiary is a party to any pending or, to the best knowledge of
Central, threatened, claim, action, suit, investigation or proceeding, or is
subject to any order, judgment or decree, except for matters which, in the
aggregate, will not have, or cannot reasonably be expected to have, a material
adverse effect on the business, financial condition or results of operations of
Central and the Central Subsidiaries taken as a whole.

     (l)  Insurance.  Central and each Central Subsidiary maintains in effect
          ---------                                                          
the insurance described (including type of policy, premiums, limits, term, and
the period

                                       7
<PAGE>
 
during which each policy has been maintained) in Schedule 2(l) and has furnished
true and correct copies of such policies to Norwest. All such policies are in
full force and effect.

     (m)  Compliance with Laws.  Central and each Central Subsidiary has all
          --------------------                                              
permits, licenses, authorizations, orders and approvals of, and has made all
filings, applications and registrations with, federal, state, local or foreign
governmental or regulatory bodies that are required in order to permit it to own
or lease its properties and assets and to carry on its business as presently
conducted and that are material to the business of Central or such Central
Subsidiary; all such permits, licenses, certificates of authority, orders and
approvals are in full force and effect and, to the best knowledge of Central, no
suspension or cancellation of any of them is threatened; and all such filings,
applications and registrations are current.  The conduct by Central and each
Central Subsidiary of its business and the condition and use of its properties
does not violate or infringe, in any respect material to any such business, any
applicable domestic (federal, state or local) or foreign law, statute,
ordinance, license or regulation.  Neither Central nor any Central Subsidiary is
in default under any order, license, regulation or demand of any federal, state,
municipal or other governmental agency or with respect to any order, writ,
injunction or decree of any court.  Except for statutory or regulatory
restrictions of general application and except as set forth on Schedule 2(m), no
federal, state, municipal or other governmental authority has placed any
restriction on the business or properties of Central or any Central Subsidiary
which reasonably could be expected to have a material adverse effect on the
business or properties of Central and the Central Subsidiaries taken as a whole.

     (n)  Labor.  No work stoppage involving Central or any Central Subsidiary
          -----                                                               
is pending or, to the best knowledge of Central, threatened.  Neither Central
nor any Central Subsidiary is involved in, or threatened with or affected by,
any labor dispute, arbitration, lawsuit or administrative proceeding which could
materially and adversely affect the business of Central or such Central
Subsidiary.  Employees of Central and the Central Subsidiaries are not
represented by any labor union nor are any collective bargaining agreements
otherwise in effect with respect to such employees.

     (o)  Material Interests of Certain Persons.  Except as set forth on
          -------------------------------------                         
Schedule 2(o), to the best knowledge of Central no officer or director of
Central or any Central Subsidiary, or any "associate" (as such term is defined
in Rule l4a-1 under the Exchange Act) of any such officer or director, has any
interest in any material contract or property (real or personal), tangible or
intangible, used in or pertaining to the business of Central or any Central
Subsidiary.

     Schedule 2(o) sets forth a correct and complete list of any loan from
Central or any Central Subsidiary to any present officer, director, employee or
any associate or related interest of any such person which was required under
Regulation O of the Federal Reserve Board to be approved by or reported to
Central's or such Central Subsidiary's Board of Directors.

                                       8
<PAGE>
 
     (p)  Central Benefit Plans.
          --------------------- 

          (i)  The only "employee benefit plans" within the meaning of Section
     3(3) of the Employee Retirement Income Security Act of 1974, as amended
     ("ERISA"), for which Central or any Central Subsidiary acts as the plan
     sponsor as defined in ERISA Section 3(16)(B), and with respect to which any
     liability under ERISA or otherwise exists or may be incurred by Central or
     any Central Subsidiary are those set forth on Schedule 2(p) (the "Plans").
     No Plan is a "multi-employer plan" within the meaning of Section 3(37) of
     ERISA.

          (ii)  Each Plan is and has been in all material respects operated and
     administered in accordance with its provisions and applicable law.  Except
     as set forth on Schedule 2(p), Central or the Central subsidiaries have
     received favorable determination letters from the Internal Revenue Service
     under the provisions of the Tax Equity and Fiscal Responsibility Act
     ("TEFRA"), the Deficit Reduction Act ("DEFRA") and the Retirement Equity
     Act ("REA") for each of the Plans to which the qualification requirements
     of Section 401(a) of the Internal Revenue Code of 1986, as amended (the
     "Code"), apply.  Central knows of no reason that any Plan which is subject
     to the qualification provisions of Section 401(a) of the Code is not
     "qualified" within the meaning of Section 401(a) of the Code and that each
     related trust is not exempt from taxation under Section 501(a) of the Code.

          (iii)  The present value of all benefits vested and all benefits
     accrued under each Plan which is subject to Title IV of ERISA did not, in
     each case, as determined for purposes of reporting on Schedule B to the
     Annual Report on Form 5500 of each such Plan as of the end of the most
     recent Plan year exceed the value of the assets of the Plan allocable to
     such vested or accrued benefits.

          (iv)  Except as disclosed in Schedule 2(p), and to the best knowledge
     of Central, no Plan or any trust created thereunder, nor any trustee,
     fiduciary or administrator thereof, has engaged in a "prohibited
     transaction", as such term is defined in Section 4975 of the Code or
     Section 406 of ERISA or violated any of the fiduciary standards under Part
     4 of Title I of ERISA which could subject, to the best knowledge of
     Central, such Plan or trust, or any trustee, fiduciary or administrator
     thereof, or any party dealing with any such Plan or trust, to the tax or
     penalty on prohibited transactions imposed by said Section 4975 or would
     result in material liability to Central and the Central Subsidiaries taken
     as a whole.

          (v)  No Plan which is subject to Title IV of ERISA or any trust
     created thereunder has been terminated, nor have there been any "reportable
     events" as that term is defined in Section 4043 of ERISA, with respect to
     any Plan, other than those events which may result from the transactions
     contemplated by this Agreement and the Merger Agreement.

                                       9
<PAGE>
 
          (vi)  No Plan or any trust created thereunder has incurred any
     "accumulated funding deficiency", as such term is defined in Section 412 of
     the Code (whether or not waived), since the effective date of ERISA.

          (vii)  Except as disclosed in Schedule 2(p), neither the execution and
     delivery of this Agreement and the Merger Agreement nor the consummation of
     the transactions contemplated hereby and thereby will (i) result in any
     material payment (including, without limitation, severance, unemployment
     compensation, golden parachute or otherwise) becoming due to any director
     or employee or former employee of Central or any Central Subsidiary under
     any Plan or otherwise, (ii) materially increase any benefits otherwise
     payable under any Plan or (iii) result in the acceleration of the time of
     payment or vesting of any such benefits to any material extent.

     (q)  Proxy Statement, etc.  None of the information regarding Central and
          --------------------                                                
the Central Subsidiaries supplied or to be supplied by Central for inclusion in
(i) a Registration Statement on Form S-4 to be filed with the SEC by Norwest for
the purpose of registering the shares of Norwest Common Stock to be exchanged
for shares of Central Common Stock pursuant to the provisions of the Merger
Agreement (the "Registration Statement"), (ii) the proxy statement to be mailed
to Central's shareholders in connection with the meeting to be called to
consider the Merger (the "Proxy Statement") and (iii) any other documents to be
filed with the SEC or any regulatory authority in connection with the
transactions contemplated hereby or by the Merger Agreement will, at the
respective times such documents are filed with the SEC or any regulatory
authority and, in the case of the Registration Statement, when it becomes
effective and, with respect to the Proxy Statement, when mailed, be false or
misleading with respect to any material fact, or omit to state any material fact
necessary in order to make the statements therein not misleading or, in the case
of the Proxy Statement or any amendment thereof or supplement thereto, at the
time of the meeting of shareholders referred to in paragraph 4(c), be false or
misleading with respect to any material fact, or omit to state any material fact
necessary to correct any statement in any earlier communication with respect to
the solicitation of any proxy for such meeting.  All documents which Central and
the Central Subsidiaries are responsible for filing with the SEC and any other
regulatory authority in connection with the Merger will comply as to form in all
material respects with the provisions of applicable law.

     (r)  Registration Obligations.  Except as set forth on Schedule 2(r),
          ------------------------                                        
neither Central nor any Central Subsidiary is under any obligation, contingent
or otherwise, which will survive the Merger by reason of any agreement to
register any of its securities under the Securities Act.

     (s)  Brokers and Finders.  Except for Keefe, Bruyette & Woods, Inc.,
          -------------------                                            
neither Central nor any Central Subsidiary nor any of their respective officers,
directors or employees has employed any broker or finder or incurred any
liability for any financial advisory fees, brokerage fees, commissions or
finder's fees, and no broker or finder has

                                       10
<PAGE>
 
acted directly or indirectly for Central or any Central Subsidiary in connection
with this Agreement and the Merger Agreement or the transactions contemplated
hereby and thereby.

     (t)  Administration of Trust Accounts.  Central and each Central Subsidiary
          --------------------------------                                      
has properly administered in all respects material and which could reasonably be
expected to be material to the financial condition of Central and the Central
Subsidiaries taken as a whole all accounts for which it acts as a fiduciary,
including but not limited to accounts for which it serves as a trustee, agent,
custodian, personal representative, guardian, conservator or investment advisor,
in accordance with the terms of the governing documents and applicable state and
federal law and regulation and common law.  Neither Central, any Central
Subsidiary, nor any director, officer or employee of Central or any Central
Subsidiary has committed any breach of trust with respect to any such fiduciary
account which is material to or could reasonably be expected to be material to
the financial condition of Central and the Central Subsidiaries taken as a
whole, and the accountings for each such fiduciary account are true and correct
in all material respects and accurately reflect the assets of such fiduciary
account.

     (u)  No Defaults.  Neither Central nor any Central Subsidiary is in
          -----------                                                   
default, nor has any event occurred which, with the passage of time or the
giving of notice, or both, would constitute a default, under any material
agreement, indenture, loan agreement or other instrument to which it is a party
or by which it or any of its assets is bound or to which any of its assets is
subject, the result of which has had or could reasonably be expected to have a
material adverse effect upon Central and the Central Subsidiaries, taken as a
whole.  To the best of Central's knowledge, all parties with whom Central or any
Central Subsidiary has material leases, agreements or contracts or who owe to
Central or any Central Subsidiary material obligations other than with respect
to those arising in the ordinary course of the banking business of the Central
Subsidiaries are in compliance therewith in all material respects.

     (v)  Environmental Liability.  There is no legal, administrative, or other
          -----------------------                                              
proceeding, claim, or action of any nature seeking to impose, or that could
result in the imposition of, on Central or any Central Subsidiary, any liability
relating to the release of hazardous substances as defined under any local,
state or federal environmental statute, regulation or ordinance including,
without limitation, the Comprehensive Environmental Response, Compensation and
Liability Act of 1980, as amended ("CERCLA"), pending or to the best of
Central's knowledge, threatened against Central or any Central Subsidiary the
result of which has had or could reasonably be expected to have a material
adverse effect upon Central and Central's Subsidiaries taken as a whole; to the
best of Central's knowledge there is no reasonable basis for any such
proceeding, claim or action; and to the best of Central's knowledge neither
Central nor any Central Subsidiary is subject to any agreement, order, judgment,
or decree by or with any court, governmental authority or third party imposing
any such environmental liability.  Central has provided Norwest with copies of
all environmental assessments, reports, studies and other related

                                       11
<PAGE>
 
information in its possession with respect to each bank facility and each non-
residential OREO property.

     3.  REPRESENTATIONS AND WARRANTIES OF NORWEST.  Norwest represents and
warrants to Central as follows:

     (a)  Organization and Authority.  Norwest is a corporation duly organized,
          --------------------------                                           
validly existing and in good standing under the laws of the State of Delaware,
is duly qualified to do business and is in good standing in all jurisdictions
where its ownership or leasing of property or the conduct of its business
requires it to be so qualified and failure to be so qualified would have a
material adverse effect on Norwest and its subsidiaries taken as a whole and has
corporate power and authority to own its properties and assets and to carry on
its business as it is now being conducted.  Norwest is registered as a bank
holding company with the Federal Reserve Board under the BHC Act.

     (b)  Norwest Subsidiaries.  Schedule 3(b) sets forth a complete and correct
          --------------------                                                  
list as of December 31, 1995, of Norwest's Significant Subsidiaries (as defined
in Regulation S-X promulgated by the SEC) (individually a "Norwest Subsidiary"
and collectively the "Norwest Subsidiaries"), all shares of the outstanding
capital stock of each of which, except as set forth in Schedule 3(b), are owned
directly or indirectly by Norwest.  No equity security of any Norwest Subsidiary
is or may be required to be issued to any person or entity other than Norwest by
reason of any option, warrant, scrip, right to subscribe to, call or commitment
of any character whatsoever relating to, or security or right convertible into,
shares of any capital stock of such subsidiary, and there are no contracts,
commitments, understandings or arrangements by which any Norwest Subsidiary is
bound to issue additional shares of its capital stock, or options, warrants or
rights to purchase or acquire any additional shares of its capital stock.
Subject to 12 U.S.C. (S) 55 (1982), all of such shares so owned by Norwest are
fully paid and nonassessable and are owned by it free and clear of any lien,
claim, charge, option, encumbrance or agreement with respect thereto.  Each
Norwest Subsidiary is a corporation or national banking association duly
organized, validly existing, duly qualified to do business and in good standing
under the laws of its jurisdiction of incorporation, and has corporate power and
authority to own or lease its properties and assets and to carry on its business
as it is now being conducted.

     (c)  Norwest Capitalization.  The authorized capital stock of Norwest
          ----------------------                                          
consists of (i) 5,000,000 shares of Preferred Stock, without par value, of which
as of the close of business on December 31, 1995, 1,127,125 shares of 10.24%
Cumulative Preferred Stock at $100 stated value, 980,000 shares of Cumulative
Tracking Preferred Stock, at $200 stated value, 12,984 shares of ESOP Cumulative
Convertible Preferred Stock, at $1,000 stated value, and 24,572 shares of 1995
ESOP Cumulative Convertible Preferred Stock, at $1,000 stated value, were
outstanding; (ii)  4,000,000 shares of Preference Stock, without par value, of
which as of the close of business on December 31, 1995, no shares were
outstanding; and (iii) 500,000,000 shares of Common Stock, $1-2/3 par value, of
which as of the close of business on December 31, 1995, 352,760,457 shares were
outstanding and 5,571,696 shares were held in the treasury.  All of the
outstanding shares of capital stock

                                       12
<PAGE>
 
of Norwest have been duly and validly authorized and issued and are fully paid
and nonassessable.

     (d)  Authorization.  Norwest has the corporate power and authority to enter
          -------------                                                         
into this Agreement and to carry out its obligations hereunder.  The execution,
delivery and performance of this Agreement by Norwest and the consummation of
the transactions contemplated hereby have been duly authorized by the Board of
Directors of Norwest.  No approval or consent by the stockholders of Norwest is
necessary for the execution and delivery of this Agreement and the Merger
Agreement and the consummation of the transactions contemplated hereby and
thereby.  Subject to such approvals of government agencies and other governing
boards having regulatory authority over Norwest as may be required by statute or
regulation, this Agreement is a valid and binding obligation of Norwest
enforceable against Norwest in accordance with its terms.

     Neither the execution, delivery and performance by Norwest of this
Agreement or the Merger Agreement, nor the consummation of the transactions
contemplated hereby and thereby, nor compliance by Norwest with any of the
provisions hereof or thereof, will (i) violate, conflict with, or result in a
breach of any provision of, or constitute a default (or an event which, with
notice or lapse of time or both, would constitute a default) under, or result in
the termination of, or accelerate the performance required by, or result in a
right of termination or acceleration of, or result in the creation of, any lien,
security interest, charge or encumbrance upon any of the properties or assets of
Norwest or any Norwest Subsidiary under any of the terms, conditions or
provisions of (x) its certificate of incorporation or by-laws or (y) any
material note, bond, mortgage, indenture, deed of trust, license, lease,
agreement or other instrument or obligation to which Norwest or any Norwest
Subsidiary is a party or by which it may be bound, or to which Norwest or any
Norwest Subsidiary or any of the properties or assets of Norwest or any Norwest
Subsidiary may be subject, or (ii) subject to compliance with the statutes and
regulations referred to in the next paragraph, to the best knowledge of Norwest,
violate any judgment, ruling, order, writ, injunction, decree, statute, rule or
regulation applicable to Norwest or any Norwest Subsidiary or any of their
respective properties or assets.

     Other than in connection with or in compliance with the provisions of the
Securities Act, the Exchange Act, the securities or blue sky laws of the various
states or filings, consents, reviews, authorizations, approvals or exemptions
required under the BHC Act or the HSR Act, and filings required to effect the
Merger under Texas law, no notice to, filing with, exemption or review by, or
authorization, consent or approval of, any public body or authority is necessary
for the consummation by Norwest of the transactions contemplated by this
Agreement and the Merger Agreement.

     (e)  Norwest Financial Statements.  The consolidated balance sheets of
          ----------------------------                                     
Norwest and Norwest's subsidiaries as of December 31, 1995 and 1994 and related
consolidated statements of income, stockholders' equity and cash flows for the
three years ended December 31, 1995, together with the notes thereto, certified
by KPMG Peat Marwick and included in Norwest's Annual Report on Form 10-K for
the fiscal year ended

                                       13
<PAGE>
 
December 31, 1995 (the "Norwest 10-K") as filed with the SEC, and the unaudited
consolidated balance sheets of Norwest and its subsidiaries as of June 30, 1996
and the related unaudited consolidated statements of income and cash flows for
the six (6) months then ended included in Norwest's Quarterly Report on Form 10-
Q for the fiscal quarter ended June 30, 1996, as filed with the SEC
(collectively, the "Norwest Financial Statements"), have been prepared in
accordance with generally accepted accounting principles applied on a consistent
basis and present fairly (subject, in the case of financial statements for
interim periods, to normal recurring adjustments) the consolidated financial
position of Norwest and its subsidiaries at the dates and the consolidated
results of operations, changes in financial position and cash flows of Norwest
and its subsidiaries for the periods stated therein.

     (f)  Reports.  Since December 31, 1990, Norwest and each Norwest Subsidiary
          -------                                                               
has filed all reports, registrations and statements, together with any required
amendments thereto, that it was required to file with (i) the SEC, including,
but not limited to, Forms 10-K, Forms 10-Q and proxy statements, (ii) the
Federal Reserve Board, (iii) the FDIC, (iv) the Comptroller and (v) any
applicable state securities or banking authorities.  All such reports and
statements filed with any such regulatory body or authority are collectively
referred to herein as the "Norwest Reports".  As of their respective dates, the
Norwest Reports complied in all material respects with all the rules and
regulations promulgated by the SEC, the Federal Reserve Board, the FDIC, the
Comptroller and any applicable state securities or banking authorities, as the
case may be, and did not contain any untrue statement of a material fact or omit
to state a material fact required to be stated therein or necessary in order to
make the statements therein, in light of the circumstances under which they were
made, not misleading.

     (g)  Properties and Leases.  Except as may be reflected in the Norwest
          ---------------------                                            
Financial Statements and except for any lien for current taxes not yet
delinquent, Norwest and each Norwest Subsidiary has good title free and clear of
any material liens, claims, charges, options, encumbrances or similar
restrictions to all the real and personal property reflected in Norwest's
consolidated balance sheet as of June 30, 1996 included in Norwest's Quarterly
Report on Form 10-Q, and all real and personal property acquired since such
date, except such real and personal property has been disposed of in the
ordinary course of business.  All leases of real property and all other leases
material to Norwest or any Norwest Subsidiary pursuant to which Norwest or such
Norwest Subsidiary, as lessee, leases real or personal property, are valid and
effective in accordance with their respective terms, and there is not, under any
such lease, any material existing default by Norwest or such Norwest Subsidiary
or any event which, with notice or lapse of time or both, would constitute such
a material default.  Substantially all Norwest's and each Norwest Subsidiary's
buildings and equipment in regular use have been well maintained and are in good
and serviceable condition, reasonable wear and tear excepted.

     (h)  Taxes.  Each of Norwest and the Norwest Subsidiaries has filed all
          -----                                                             
material federal, state, county, local and foreign tax returns, including
information returns, required to be filed by it, and paid or made adequate
provision for the payment of all taxes owed by

                                       14
<PAGE>
 
it, including those with respect to income, withholding, social security,
unemployment, workers compensation, franchise, ad valorem, premium, excise and
sales taxes, and no taxes shown on such returns to be owed by it or assessments
received by it are delinquent. The federal income tax returns of Norwest and the
Norwest Subsidiaries for the fiscal year ended December 31, 1979, and for all
fiscal years prior thereto, are for the purposes of routine audit by the
Internal Revenue Service closed because of the statute of limitations, and no
claims for additional taxes for such fiscal years are pending. Except only as
set forth on Schedule 3(h), (i) neither Norwest nor any Norwest Subsidiary is a
party to any pending action or proceeding, nor to Norwest's knowledge is any
such action or proceeding threatened by any governmental authority, for the
assessment or collection of taxes, interest, penalties, assessments or
deficiencies which could reasonably be expected to have any material adverse
effect on Norwest and its subsidiaries taken as a whole, and (ii) no issue has
been raised by any federal, state, local or foreign taxing authority in
connection with an audit or examination of the tax returns, business or
properties of Norwest or any Norwest Subsidiary which has not been settled,
resolved and fully satisfied, or adequately reserved for. Each of Norwest and
the Norwest Subsidiaries has paid all taxes owed or which it is required to
withhold from amounts owing to employees, creditors or other third parties.

     (i)  Absence of Certain Changes.  Since December 31, 1995, there has been
          --------------------------                                          
no change in the business, financial condition or results of operations of
Norwest or any Norwest Subsidiary which has had, or may reasonably be expected
to have, a material adverse effect on the business, financial condition or
results of operations of Norwest and its subsidiaries taken as a whole.

     (j)  Commitments and Contracts.  Except as set forth on Schedule 3(j), as
          -------------------------                                           
of May 1, 1996 neither Norwest nor any Norwest Subsidiary is a party or subject
to any of the following (whether written or oral, express or implied):

          (i)  any labor contract or agreement with any labor union;

          (ii)  any contract not made in the ordinary course of business
     containing covenants which materially limit the ability of Norwest or any
     Norwest Subsidiary to compete in any line of business or with any person or
     which involve any material restriction of the geographical area in which,
     or method by which, Norwest or any Norwest Subsidiary may carry on its
     business (other than as may be required by law or applicable regulatory
     authorities);

          (iii)  any other contract or agreement which is a "material contract"
     within the meaning of Item 601(b)(10) of Regulation S-K.

     (k)  Litigation and Other Proceedings.  Neither Norwest nor any Norwest
          --------------------------------                                  
Subsidiary is a party to any pending or, to the best knowledge of Norwest,
threatened, claim, action, suit, investigation or proceeding, or is subject to
any order, judgment or decree, except for matters which, in the aggregate, will
not have, or cannot reasonably be

                                       15
<PAGE>
 
expected to have, a material adverse effect on the business, financial condition
or results of operations of Norwest and its subsidiaries taken as a whole.

     (l)  Insurance.  Norwest and each Norwest Subsidiary is presently insured
          ---------                                                           
or self insured, and during each of the past five calendar years (or during such
lesser period of time as Norwest has owned such Norwest Subsidiary) has been
insured or self-insured, for reasonable amounts with financially sound and
reputable insurance companies against such risks as companies engaged in a
similar business would, in accordance with good business practice, customarily
be insured and has maintained all insurance required by applicable law and
regulation.

     (m)  Compliance with Laws.  Norwest and each Norwest Subsidiary has all
          --------------------                                              
permits, licenses, authorizations, orders and approvals of, and has made all
filings, applications and registrations with, federal, state, local or foreign
governmental or regulatory bodies that are required in order to permit it to own
or lease its properties or assets and to carry on its business as presently
conducted and that are material to the business of Norwest or such Subsidiary;
all such permits, licenses, certificates of authority, orders and approvals are
in full force and effect, and to the best knowledge of Norwest, no suspension or
cancellation of any of them is threatened; and all such filings, applications
and registrations are current.  The conduct by Norwest and each Norwest
Subsidiary of its business and the condition and use of its properties does not
violate or infringe, in any respect material to any such business, any
applicable domestic (federal, state or local) or foreign law, statute,
ordinance, license or regulation.  Neither Norwest nor any Norwest Subsidiary is
in default under any order, license, regulation or demand of any federal, state,
municipal or other governmental agency or with respect to any order, writ,
injunction or decree of any court.  Except for statutory or regulatory
restrictions of general application, no federal, state, municipal or other
governmental authority has placed any restrictions on the business or properties
of Norwest or any Norwest Subsidiary which reasonably could be expected to have
a material adverse effect on the business or properties of Norwest and its
subsidiaries taken as a whole.

     (n)  Labor.  No work stoppage involving Norwest or any Norwest Subsidiary
          -----                                                               
is pending or, to the best knowledge of Norwest, threatened.  Neither Norwest
nor any Norwest Subsidiary is involved in, or threatened with or affected by,
any labor dispute, arbitration, lawsuit or administrative proceeding which could
materially and adversely affect the business of Norwest or such Norwest
Subsidiary.  Except as set forth on Schedule 3(j), employees of Norwest and the
Norwest Subsidiaries are not represented by any labor union nor are any
collective bargaining agreements otherwise in effect with respect to such
employees.

     (o)  Norwest Benefit Plans.
          --------------------- 

          (i)  As of May 1, 1996, the only "employee benefit plans" within the
     meaning of Section 3(3) of ERISA for which Norwest or any Norwest
     Subsidiary acts as plan sponsor as defined in ERISA Section 3(16)(B) with
     respect to which

                                       16
<PAGE>
 
     any liability under ERISA or otherwise exists or may be incurred by Norwest
     or any Norwest Subsidiary are those set forth on Schedule 3(o) (the
     "Norwest Plans"). No Norwest Plan is a "multi-employer plan" within the
     meaning of Section 3(37) of ERISA.

          (ii)  Each Norwest Plan is and has been in all material respects
     operated and administered in accordance with its provisions and applicable
     law.  Except as set forth on Schedule 3(o), Norwest or the Norwest
     Subsidiaries have received favorable determination letters from the
     Internal Revenue Service under the provisions of TEFRA, DEFRA and REA for
     each of the Norwest Plans to which the qualification requirements of
     Section 401(a) of the Code apply.  Norwest knows of no reason that any
     Norwest Plan which is subject to the qualification provisions of Section
     401(a) of the Code is not "qualified" within the meaning of Section 401(a)
     of the Code and that each related trust is not exempt from taxation under
     Section 501(a) of the Code.

          (iii)  The present value of all benefits vested and all benefits
     accrued under each Norwest Plan which is subject to Title IV of ERISA did
     not, in each case, as determined for purposes of reporting on Schedule B to
     the Annual Report on Form 5500 of each such Norwest Plan as of the end of
     the most recent Plan year, exceed the value of the assets of the Norwest
     Plans allocable to such vested or accrued benefits.

          (iv)  Except as set forth on Schedule 3(o), and to the best knowledge
     of Norwest, no Norwest Plan or any trust created thereunder, nor any
     trustee, fiduciary or administrator thereof, has engaged in a "prohibited
     transaction", as such term is defined in Section 4975 of the Code or
     Section 406 of ERISA or violated fiduciary  standards under Part 4 of Title
     I of ERISA, which could subject, to the best knowledge of Norwest, such
     Norwest Plan or trust, or any trustee, fiduciary or administrator thereof,
     or any party dealing with any such Norwest Plan or trust, to the tax or
     penalty on prohibited transactions imposed by said Section 4975 or would
     result in material liability to Norwest and its subsidiaries taken as a
     whole.

          (v)  Except as set forth on Schedule 3(o), no Norwest Plan which is
     subject to Title IV of ERISA or any trust created thereunder has been
     terminated, nor have there been any "reportable events" as that term is
     defined in Section 4043 of ERISA with respect to any Norwest Plan, other
     than those events which may result from the transactions contemplated by
     this Agreement and the Merger Agreement.

          (vi)  No Norwest Plan or any trust created thereunder has incurred any
     "accumulated funding deficiency", as such term is defined in Section 412 of
     the Code (whether or not waived), during the last five Norwest Plan years
     which would result in a material liability.

                                       17
<PAGE>
 
          (vii)  Neither the execution and delivery of this Agreement and the
     Merger Agreement nor the consummation of the transactions contemplated
     hereby and thereby will (i) result in any material payment (including,
     without limitation, severance, unemployment compensation, golden parachute
     or otherwise) becoming due to any director or employee or former employee
     of Norwest under any Norwest Plan or otherwise, (ii) materially increase
     any benefits otherwise payable under any Norwest Plan or (iii) result in
     the acceleration of the time of payment or vesting of any such benefits to
     any material extent.

     (p)  Registration Statement, etc.  None of the information regarding
          ---------------------------                                    
Norwest and its subsidiaries supplied or to be supplied by Norwest for inclusion
in (i) the Registration Statement, (ii) the Proxy Statement, or (iii) any other
documents to be filed with the SEC or any regulatory authority in connection
with the transactions contemplated hereby or by the Merger Agreement will, at
the respective times such documents are filed with the SEC or any regulatory
authority and, in the case of the Registration Statement, when it becomes
effective and, with respect to the Proxy Statement, when mailed, be false or
misleading with respect to any material fact, or omit to state any material fact
necessary in order to make the statements therein not misleading or, in the case
of the Proxy Statement or any amendment thereof or supplement thereto, at the
time of the meeting of shareholders referred to in paragraph 4(c), be false or
misleading with respect to any material fact, or omit to state any material fact
necessary to correct any statement in any earlier communication with respect to
the solicitation of any proxy for such meeting.  All documents which Norwest and
the Norwest Subsidiaries are responsible for filing with the SEC and any other
regulatory authority in connection with the Merger will comply as to form in all
material respects with the provisions of applicable law.

     (q)  Brokers and Finders.  Neither Norwest nor any Norwest Subsidiary nor
          -------------------                                                 
any of their respective officers, directors or employees has employed any broker
or finder or incurred any liability for any financial advisory fees, brokerage
fees, commissions or finder's fees, and no broker or finder has acted directly
or indirectly for Norwest or any Norwest Subsidiary in connection with this
Agreement and the Merger Agreement or the transactions contemplated hereby and
thereby.

     (r)  No Defaults.  Neither Norwest nor any Norwest Subsidiary is in
          -----------                                                   
default, nor has any event occurred which, with the passage of time or the
giving of notice, or both, would constitute a default under any material
agreement, indenture, loan agreement or other instrument to which it is a party
or by which it or any of its assets is bound or to which any of its assets is
subject, the result of which has had or could reasonably be expected to have a
material adverse effect upon Norwest and its subsidiaries taken as a whole.  To
the best of Norwest's knowledge, all parties with whom Norwest or any Norwest
Subsidiary has material leases, agreements or contracts or who owe to Norwest or
any Norwest Subsidiary material obligations other than with respect to those
arising in the ordinary course of the banking business of the Norwest
Subsidiaries are in compliance therewith in all material respects.

                                       18
<PAGE>
 
     (s)  Environmental Liability.  There is no legal, administrative, or other
          -----------------------                                              
proceeding, claim, or action of any nature seeking to impose, or that could
result in the imposition, on Norwest or any Norwest Subsidiary of any liability
relating to the release of hazardous substances as defined under any local,
state or federal environmental statute, regulation or ordinance including,
without limitation, CERCLA, pending or to the best of Norwest's knowledge,
threatened against Norwest or any Norwest Subsidiary, the result of which has
had or could reasonably be expected to have a material adverse effect upon
Norwest and its subsidiaries taken as a whole; to the best of Norwest's
knowledge there is no reasonable basis for any such proceeding, claim or action;
and to the best of Norwest's knowledge neither Norwest nor any Norwest
Subsidiary is subject to any agreement, order, judgment, or decree by or with
any court, governmental authority or third party imposing any such environmental
liability.

     (t)  Merger Co.  As of the Closing Date, Merger Co. will be a corporation
          ---------                                                           
duly organized, validly existing, duly qualified to do business and in good
standing under the laws of its jurisdiction of incorporation, and will have
corporate power and authority to own or lease its properties and assets and to
carry on its business.

     (u)  Regulatory Approval. Norwest is aware of no circumstance, in existence
          -------------------                                                   
as of the date hereof, which would prevent the transactions contemplated by this
Agreement and the Merger Agreement from being approved by the Federal Reserve
Board.

     4.  COVENANTS OF CENTRAL.  Central covenants and agrees with Norwest as
follows:

     (a)  Except as otherwise permitted or required by this Agreement, from the
date hereof until the Effective Time of the Merger, Central, and each Central
Subsidiary will:  maintain its corporate existence in good standing; maintain
the general character of its business and conduct its business in its ordinary
and usual manner; extend credit in accordance with existing lending policies,
except that it shall not, without the prior written consent of Norwest (which
consent requirement shall be deemed to be waived as to any loan approval request
to which Norwest has made no response by the end of the second business day
following the day of receipt of the request by a representative designated by
Norwest in writing) (A) make any extensions of credit aggregating in excess of
$500,000 to a person or entity that is not a borrower as of the date hereof, or
(B) engage in any loan transaction or series of contemporaneous loan
transactions involving an aggregate of more than $250,000 with any borrower who
has aggregate extensions of credit in excess of $1,000,000 as of the date
hereof; maintain proper business and accounting records in accordance with
generally accepted principles, provided, however, that Central agrees to
implement and to cause the Central Subsidiaries to implement Central's
restructuring plan, as disclosed to Norwest as of the date hereof; maintain its
properties in good repair and condition, ordinary wear and tear excepted;
maintain in all material respects presently existing insurance coverage; use its
best efforts to preserve its business organization intact, to keep the services
of its present principal employees and to preserve its good will and the good
will of its suppliers, customers and others having

                                       19
<PAGE>
 
business relationships with it; use its best efforts to obtain any approvals or
consents required to maintain existing leases and other contracts in effect
following the Merger; comply in all material respects with all laws,
regulations, ordinances, codes, orders, licenses and permits applicable to the
properties and operations of Central and each Central Subsidiary the non-
compliance with which reasonably could be expected to have a material adverse
effect on Central and the Central Subsidiaries taken as a whole; and permit
Norwest and its representatives (including KPMG Peat Marwick LLP) upon prior
notice to Central to examine its and its subsidiaries books, records and
properties and to interview officers, employees and agents at all reasonable
times when it is open for business. No such examination by Norwest or its
representatives either before or after the date of this Agreement shall in any
way affect, diminish or terminate any of the representations, warranties or
covenants of Central herein expressed.

     (b)  Except as otherwise contemplated or required by this Agreement, from
the date hereof until the Effective Time of the Merger, Central and each Central
subsidiary will not (without the prior written consent of Norwest):  amend or
otherwise change its articles of incorporation or association or by-laws; issue
or sell or authorize for issuance or sale, or grant any options or make other
agreements with respect to the issuance or sale or conversion of, any shares of
its capital stock, phantom shares or other share-equivalents, or any other of
its securities, except that Central may issue shares of Central Common Stock
upon the exercise of outstanding stock options described in Schedule 4(b);
authorize or incur any long-term debt (other than deposit liabilities);
mortgage, pledge or subject to lien or other encumbrance any of its properties,
except in the ordinary course of business; enter into any material agreement,
contract or commitment in excess of $50,000 except banking transactions in the
ordinary course of business and in accordance with policies and procedures in
effect on the date hereof; make any investments except investments made in the
ordinary course of business, in accordance with past practice; amend or
terminate any Plan except as required by law; make any contributions to any Plan
except as required by the terms of such Plan in effect as of the date hereof;
declare, set aside, make or pay any dividend or other distribution with respect
to its capital stock except (i) between the date hereof and the record date for
the regular cash dividend, if any, declared on Norwest Common Stock for the
second quarter of 1997 ("Record Date"), the Board of Directors of Central may
declare and pay, in accordance with past practice, dividends not to exceed an
annualized rate of $0.40 per share of Central Common Stock, (ii) if the
Effective Date of the Merger is after the Record Date, Central may declare and
pay cash dividends on Central Common Stock in an amount not to exceed, in the
aggregate, the amount which would have been received by the holders of 4,700,000
shares of Norwest Common Stock between such Record Date and the Effective Date
of the Merger,  provided, however, that the shareholders of Central shall be
entitled to either a dividend on Central Common Stock or Norwest Common Stock,
but not both, in the calendar quarter in which the Closing shall occur, and
(iii) any dividend declared by the Board of Directors of a Central Subsidiary in
accordance with applicable law and regulation; redeem, purchase or otherwise
acquire, directly or indirectly, any of the capital stock of Central; increase
the compensation of any officers, directors or executive employees, except
pursuant to existing compensation plans and

                                       20
<PAGE>
 
practices (including bonus plans), provided, however, that Central may, in
addition, accrue and pay bonuses and deferred compensation obligations in
accordance with Schedule 4(b) attached hereto, and provided, further, however,
that such bonus and deferred compensation amounts shall be calculated without
regard to the effect of the accruals and reserves taken in accordance with
paragraph 4(m) hereof; sell or otherwise dispose of any shares of the capital
stock of any Central Subsidiary; or sell or otherwise dispose of any of its
assets or properties other than in the ordinary course of business.

     (c)  The Board of Directors of Central will duly call, and will cause to be
held not later than twenty-five (25) business days following the effective date
of the Registration Statement referred to in paragraph 5(c) hereof, a meeting of
its shareholders and will direct that this Agreement and the Merger Agreement be
submitted to a vote at such meeting.  The Board of Directors of Central will (i)
cause proper notice of such meeting to be given to its shareholders in
compliance with the Texas Business Corporation Act and other applicable law and
regulation, and (ii) except to the extent that the Board of Directors of Central
shall conclude in good faith, after taking into account the advice of counsel,
that to do so would violate its fiduciary obligations under applicable law, (A)
recommend by the affirmative vote of the Board of Directors a vote in favor of
approval of this Agreement and the Merger Agreement, and (B) use its best
efforts to solicit from its shareholders proxies in favor thereof.

     (d)  Central will furnish or cause to be furnished to Norwest all the
information concerning Central and its subsidiaries required for inclusion in
the Registration Statement referred to in paragraph 5(c) hereof, or any
statement or application made by Norwest to any governmental body in connection
with the transactions contemplated by this Agreement. Any financial statement
for any fiscal year provided under this paragraph must include the audit opinion
and the consent of KMPG Peat Marwick LLP to use such opinion in such
Registration Statement.

     (e)  Central will take all necessary corporate and other action and use its
best efforts to obtain all approvals of regulatory authorities, consents and
other approvals required of Central to carry out the transactions contemplated
by this Agreement and will cooperate with Norwest to obtain all such approvals
and consents required of Norwest.

     (f)  Central will use its best efforts to deliver to the Closing all
opinions, certificates and other documents required to be delivered by it at the
Closing.

     (g)  Central will hold in confidence all documents and information
concerning Norwest and its subsidiaries furnished to Central and its
representatives in connection with the transactions contemplated by this
Agreement and will not release or disclose such information to any other person,
except as required by law and except to Central's outside professional advisers
in connection with this Agreement, with the same undertaking from such
professional advisers.  If the transactions contemplated by this Agreement shall
not be consummated, such confidence shall be maintained and such information
shall not be used in competition with Norwest (except to the extent that such
information can be

                                       21
<PAGE>
 
shown to be previously known to Central, in the public domain, or later acquired
by Central from other legitimate sources) and, upon request, all such documents,
any copies thereof and extracts therefrom shall immediately thereafter be
returned to Norwest.

     (h)  Neither Central, nor any Central Subsidiary, nor any director,
officer, representative or agent thereof, will, directly or indirectly, solicit,
authorize the solicitation of or except to the extent that the Board of
Directors of Central shall conclude in good faith, after taking into account the
written advice of its outside counsel, that to fail to do so could reasonably be
determined to violate its fiduciary obligations under applicable law, enter into
any negotiations with any corporation, partnership, person or other entity or
group (other than Norwest) concerning any offer or possible offer (i) except as
otherwise permitted by paragraph 4(b) with respect to the Central Options, to
purchase any shares of common stock, any option or warrant to purchase any
shares of common stock, any securities convertible into any shares of such
common stock, or any other equity security of Central or any Central Subsidiary,
(ii) to make a tender or exchange offer for any shares of such common stock or
other equity security, (iii) to purchase, lease or otherwise acquire the assets
of Central or any Central Subsidiary except in the ordinary course of business,
or (iv) to merge, consolidate or otherwise combine with Central or any Central
Subsidiary.  If any corporation, partnership, person or other entity or group
makes an offer or inquiry to Central or any Central Subsidiary concerning any of
the foregoing, Central or such Central Subsidiary will promptly disclose such
offer or inquiry, including the terms thereof, to Norwest.

     (i)  Central shall consult with Norwest as to the form and substance of any
proposed press release or other proposed public disclosure of matters related to
this Agreement or any of the transactions contemplated hereby.

     (j)  Central and each Central Subsidiary will take all action necessary or
required (i) to terminate or amend, if requested by Norwest, all qualified
pension and welfare benefit plans and all non-qualified benefit plans and
compensation arrangements as of the Effective Date of the Merger to facilitate
the merger of such plans with Norwest plans without gaps in coverage for
participants in the plans and without duplication of costs caused by the
continuation of such plans after coverage is available under Norwest plans, and
(ii) to submit application to the Internal Revenue Service for a favorable
determination letter for each of the Plans which is subject to the qualification
requirements of Section 401(a) of the Code prior to the Effective Date of the
Merger.

     (k)  Neither Central nor any Central Subsidiary shall take any action which
with respect to Central would disqualify the Merger as a "pooling of interests"
for accounting purposes.

     (l)  Central shall use its best efforts to obtain and deliver at least 32
days prior to the Effective Date of the Merger signed representations
substantially in the form attached hereto as Exhibit B to Norwest by each
executive officer, director or shareholder of

                                       22
<PAGE>
 
Central who may reasonably be deemed an "affiliate" of Central within the
meaning of such term as used in Rule 145 under the Securities Act.

     (m) Central shall establish such additional accruals and reserves as may be
necessary to conform Central's accounting and credit loss reserve practices and
methods to those of Norwest and Norwest's plans with respect to the conduct of
Central's business following the Merger and, to the extent permitted by
generally accepted accounting principles,  to provide for the costs and expenses
relating to the consummation by Central of the Merger and the other transactions
contemplated by this Agreement.

     (n) Central shall obtain, at its sole expense, Phase I environmental
assessments for each bank facility and each non-residential OREO property.  Oral
reports of such environmental assessments shall be delivered to Norwest no later
than four (4) weeks and written reports shall be delivered to Norwest no later
than eight (8) weeks from the date of this Agreement.  Central shall obtain, at
its sole expense, Phase II environmental assessments for properties identified
by Norwest on the basis of the results of such Phase I environmental
assessments.  Central shall obtain a survey and assessment of all potential
asbestos containing material in owned or leased properties (other than OREO
property)  and a written report of the results shall be delivered to Norwest
within four (4) weeks of execution of the definitive agreement.

     (o) Central shall obtain, at its sole expense, commitments for title
insurance and boundary surveys for each bank facility which shall be delivered
to Norwest no later than four (4) weeks from the date of this Agreement.

     5.  COVENANTS OF NORWEST.  Norwest covenants and agrees with Central as
follows:

     (a)  From the date hereof until the Effective Time of the Merger, Norwest
will maintain its corporate existence in good standing; conduct, and cause the
Norwest Subsidiaries to conduct, their respective businesses in compliance with
all material obligations and duties imposed on them by all laws, governmental
regulations, rules and ordinances, and judicial orders, judgments and decrees
applicable to Norwest or the Norwest Subsidiaries, their businesses or their
properties; maintain all books and records of it and the Norwest Subsidiaries,
including all financial statements, in accordance with the accounting principles
and practices consistent with those used for the Norwest Financial Statements,
except for changes in such principles and practices required under generally
accepted accounting principles.

     (b)  Norwest will furnish to Central all the information concerning Norwest
required for inclusion in a proxy statement or statements to be sent to the
shareholders of Central, or in any statement or application made by Central to
any governmental body in connection with the transactions contemplated by this
Agreement.

                                       23
<PAGE>
 
     (c)  As promptly as practicable after the execution of this Agreement,
Norwest will file with the SEC a registration statement on Form S-4 (the
"Registration Statement") under the Securities Act and any other applicable
documents, relating to the shares of Norwest Common Stock to be delivered to the
shareholders of Central pursuant to the Merger Agreement, and will use its best
efforts to cause the Registration Statement to become effective.  At the time
the Registration Statement becomes effective, the Registration Statement will
comply in all material respects with the provisions of the Securities Act and
the published rules and regulations thereunder, and will not contain any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not false or
misleading, and at the time of mailing thereof to the Central shareholders, at
the time of the Central shareholders' meeting referred to in paragraph 4(c)
hereof and at the Effective Time of the Merger the prospectus included as part
of the Registration Statement, as amended or supplemented by any amendment or
supplement filed by Norwest (hereinafter the "Prospectus"), will not contain any
untrue statement of a material fact or omit to state any material fact necessary
to make the statements therein not false or misleading; provided, however, that
                                                        --------  -------      
none of the provisions of this subparagraph shall apply to statements in or
omissions from the Registration Statement or the Prospectus made in reliance
upon and in conformity with information furnished by Central or any Central
subsidiary for use in the Registration Statement or the Prospectus.

     (d)  Norwest will file all documents required to be filed to list the
Norwest Common Stock to be issued pursuant to the Merger Agreement on the New
York Stock Exchange and the Chicago Stock Exchange and use its best efforts to
effect said listings.

     (e)  The shares of Norwest Common Stock to be issued by Norwest to the
shareholders of Central pursuant to this Agreement and the Merger Agreement
will, upon such issuance and delivery to said shareholders pursuant to the
Merger Agreement, be duly authorized, validly issued, fully paid and
nonassessable.  The shares of Norwest Common Stock to be delivered to the
shareholders of Central pursuant to the Merger Agreement are and will be free of
any preemptive rights of the stockholders of Norwest.

     (f)  Norwest will file all documents required to obtain, prior to the
Effective Time of the Merger, all necessary Blue Sky permits and approvals, if
any, required to carry out the transactions contemplated by this Agreement, will
pay all expenses incident thereto and will use its best efforts to obtain such
permits and approvals.

     (g)  Norwest will take all necessary corporate and other action and file
all documents required to obtain and will use its best efforts to obtain all
approvals of regulatory authorities, consents and approvals required of it to
carry out the transactions contemplated by this Agreement and will cooperate
with Central to obtain all such approvals and consents required by Central.

     (h)  Norwest will hold in confidence all documents and information
concerning Central and Central's Subsidiaries furnished to it and its
representatives in connection with

                                       24
<PAGE>
 
the transactions contemplated by this Agreement and will not release or disclose
such information to any other person, except as required by law and except to
its outside professional advisers in connection with this Agreement, with the
same undertaking from such professional advisers. If the transactions
contemplated by this Agreement shall not be consummated, such confidence shall
be maintained and such information shall not be used in competition with Central
(except to the extent that such information can be shown to be previously known
to Norwest, in the public domain, or later acquired by Norwest from other
legitimate sources) and, upon request, all such documents, copies thereof or
extracts therefrom shall immediately thereafter be returned to Central. If the
transactions contemplated by this Agreement shall not be consummated, Norwest
agrees that for a period of eighteen (18) months following termination of this
Agreement Norwest will not directly solicit for employment any officer or
employee of Central who was introduced to Norwest during its due diligence
review of Central prior to the date hereof; provided, however, that nothing
herein shall prohibit Norwest from interviewing or hiring any officer or
employee of Central who responds to a general employment solicitation placed by
or on behalf of Norwest in a publication of general circulation.

     (i)  Norwest will file any documents or agreements required to be filed in
connection with the Merger under the Texas Business Corporation Act.

     (j)  Norwest will use its best efforts to deliver to the Closing all
opinions, certificates and other documents required to be delivered by it at the
Closing.

     (k)  Norwest shall consult with Central as to the form and substance of any
proposed press release or other proposed public disclosure of matters related to
this Agreement or any of the transactions contemplated hereby.

     (l)  Norwest shall furnish Central with copies, prior to filing, of the
nonconfidential portions of the applications referred to in paragraph 7(e) and
shall give Central notice of receipt of the regulatory approvals referred to in
paragraph 7(e).

     (m)  Neither Norwest nor any Norwest Subsidiary shall take any action which
with respect to Norwest would disqualify the Merger as a "pooling of interests"
for accounting purposes.  Norwest shall use its best efforts to obtain and
deliver to Central, prior to the Effective Date of the Merger, signed
representations from the directors and executive officers of Norwest to the
effect that, except for de minimus  dispositions which will not disqualify the
Merger as a pooling of interests, they will not dispose of shares of Norwest or
Central during the period commencing 30 days prior to the Effective Date and
ending upon publication by Norwest of financial results including at least 30
days of combined operations of Central and Norwest.

     (n)  For a period not exceeding fifteen days prior to the Closing Date,
Norwest will permit Central and its representatives to examine its books,
records and properties and interview officers, employees and agents of Norwest
at all reasonable times when it is open for business.  No such examination by
Central or its representatives shall in any way

                                       25
<PAGE>
 
affect, diminish or terminate any of the representations, warranties or
covenants of Norwest herein expressed.

     (o)  Norwest shall take such actions on its part as may be necessary to
cause each Central Option outstanding immediately prior to the Effective Time of
the Merger to become and represent an option to purchase (i) the number of
shares of Norwest Common Stock (a "Substitute Option") determined by multiplying
the number of shares of Central Common Stock subject to such Central Option by
the Norwest Share Amount, at an exercise price per share of Norwest Common Stock
equal to the exercise price per share of Central Common Stock divided by the
Norwest Share Amount.  After the Effective Time of the Merger, each Substitute
Option shall be exercisable upon the same terms and conditions as were
applicable to the related Central Option immediately prior to the Effective Time
of the Merger except that the exercise price per share of Norwest Common Stock
shall be as provided above in this paragraph 5(o).  The number of shares of
Norwest Common Stock subject to each Substitute Option, as determined herein,
shall be rounded to the nearest whole share.  Norwest shall (i) register under
the Securities Act on Form S-8 or other appropriate form (and use its best
efforts to maintain the effectiveness thereof) all shares of Norwest Common
Stock issuable pursuant to the Substitute Options, (ii) cause such shares to be
authorized for listing on the New York Stock Exchange and the Chicago Stock
Exchange, and (iii) reserve a sufficient number of such shares for issuance upon
such exercise.

     (p)  With respect to the indemnification of directors and officers and with
respect to directors' and officers' insurance, Norwest agrees as follows:

          (i)  Norwest shall ensure that all rights to indemnification and all
     limitations of liability existing in favor of any person who is now, or has
     been at any time prior to the date hereof, or who becomes prior to the
     Effective Time of the Merger, a director or officer of Central or any
     Central Subsidiary, (an "Indemnified Party" and, collectively, the
     "Indemnified Parties") in Central 's Articles of Incorporation or By-laws
     or similar governing documents of any Central Subsidiary, as applicable in
     the particular case and as in effect on the date hereof, shall, with
     respect to claims arising from (A) facts or events that occurred before the
     Effective Time of the Merger, or (B) this Agreement or any of the
     transactions contemplated by this Agreement, whether in any case asserted
     or arising before or after the Effective Time of the Merger, survive the
     Merger and shall continue in full force and effect.  Nothing contained in
     this paragraph 5(p)(i) shall be deemed to preclude the liquidation,
     consolidation or merger of Central or any Central Subsidiary, in which case
     all of such rights to indemnification and limitations on liability shall be
     deemed to survive and continue as contractual rights notwithstanding any
     such liquidation or consolidation or merger; provided, however, that in the
                                                  --------  -------             
     event of liquidation or sale of substantially all of the assets of Central,
     Norwest shall guarantee, to the extent of the net asset value of Central or
     any Central Subsidiary as of the Effective Date of the Merger, the
     indemnification obligations of Central or any Central Subsidiary to the
     extent of indemnification obligations of Central and the

                                       26
<PAGE>
 
     Central Subsidiaries described above. Notwithstanding anything to the
     contrary contained in this paragraph 5(p)(i), nothing contained herein
     shall require Norwest to indemnify any person who was a director or officer
     of Central or any Central Subsidiary to a greater extent than Central or
     any Central Subsidiary is, as of the date of this Agreement, required to
     indemnify any such person;

          (ii)  any Indemnified Party wishing to claim indemnification under
     paragraph 5(p)(i), upon learning of any such claim, action, suit,
     proceeding or investigation, shall promptly notify Norwest thereof, but the
     failure to so notify shall not relieve Norwest of any liability it may have
     to such Indemnified Party.  In the event of any such claim, action, suit,
     proceeding or investigation (whether arising before or after the Effective
     Time of the Merger), (A) Norwest shall have the right to assume the defense
     thereof and Norwest shall not be liable to any Indemnified Party for any
     legal expenses of other counsel or any other expenses subsequently incurred
     by such Indemnified Party in connection with the defense thereof, except
     that if Norwest elects not to assume such defense or counsel for the
     Indemnified Party advises that there are issues which raise conflicts of
     interest between Norwest and the Indemnified Party, the Indemnified Party
     may retain counsel satisfactory to them, and Norwest shall pay the
     reasonable fees and expenses of such counsel for the Indemnified Party
     promptly as statements therefor are received; provided, however, that
                                                   --------  -------      
     Norwest shall be obligated pursuant to this subparagraph (ii) to pay for
     only one firm of counsel for all Indemnified Parties in any jurisdiction
     unless the use of one counsel for such Indemnified Parties would present
     such counsel with a conflict of interest and (B) such Indemnified Party
     shall cooperate in the defense of any such matter;

          (iii)  for a period of three years after the Effective Time of the
     Merger, Norwest shall use its best efforts to cause to be maintained in
     effect the current policies of directors' and officers' liability insurance
     maintained by Central (provided that Norwest may substitute therefor
     policies of at least the same coverage and amount containing terms and
     conditions which are substantially no less advantageous) with respect to
     claims arising from facts or events which occurred before the Effective
     Time of the Merger; provided, however, that Norwest shall not be required
                         --------  -------                                    
     to maintain the coverage for employees (other than directors and officers)
     which is currently included in the directors' and officers' liability
     policies maintained by Central;  and provided, further, however, that in no
                                          ----------------------------          
     event shall Norwest be obligated to expend, in order to maintain or provide
     insurance coverage pursuant to this paragraph 5(p)(iii), any amount per
     annum in excess of 125% of the amount of the annual premiums paid as of the
     date hereof by Central for such insurance (the "Maximum Amount") and
     provided further that, prior to the Effective Time of the Merger, Central
     shall notify the appropriate directors' and officers' liability insurers of
     the Merger and of all pending or threatened claims, actions, suits,
     proceedings or investigations asserted or claimed against any Indemnified
     Party, or circumstances likely to give rise thereto, in accordance with
     terms and conditions of the applicable policies.  If the amount of

                                       27
<PAGE>
 
     the annual premiums necessary to maintain or procure such insurance
     coverage exceeds the Maximum Amount, Norwest shall use reasonable efforts
     to maintain the most advantageous policies of directors' and officers'
     insurance obtainable for an annual premium equal to the Maximum Amount;

          (iv)  if Norwest or any of its successors or assigns (A) shall
     consolidate with or merge into any other corporation or entity and shall
     not be the continuing or surviving corporation or entity of such
     consolidation or merger or (B) shall transfer all or substantially all of
     its properties and assets to any individual, corporation or other entity,
     then and in each such case, proper provision shall be made so that the
     successors and assigns of Norwest shall assume the obligations set forth in
     this paragraph 5(p); and

          (v)  the provisions of this paragraph 5(p) are intended to be for the
     benefit of, and shall be enforceable by, each Indemnified Party and his or
     her heirs and representatives.

     6.  CONDITIONS PRECEDENT TO OBLIGATION OF CENTRAL.  The obligation of
Central to effect the Merger shall be subject to the satisfaction at or before
the Time of Filing of the following further conditions, which may be waived in
writing by Central:

     (a)  Except as they may be affected by transactions contemplated hereby and
except to the extent such representations and warranties are by their express
provisions made as of a specified date and except for activities or transactions
after the date of this Agreement made in the ordinary course of business and not
expressly prohibited by this Agreement, the representations and warranties
contained in paragraph 3 hereof shall be true and correct in all respects
material to Norwest and its subsidiaries taken as a whole as if made at the Time
of Filing.

     (b)  Norwest shall have, or shall have caused to be, performed and observed
in all material respects all covenants, agreements and conditions hereof to be
performed or observed by it and Merger Co. at or before the Time of Filing.

     (c)  Central shall have received a favorable certificate, dated as of the
Effective Date of the Merger, signed by the Chairman, the President or any
Executive Vice President or Senior Vice President and by the Secretary or
Assistant Secretary of Norwest, as to the matters set forth in subparagraphs (a)
and (b) of this paragraph 6.

     (d)  This Agreement and the Merger Agreement shall have been approved by
the affirmative vote of the holders of the percentage of the outstanding shares
of Central required for approval of a plan of merger in accordance with the
provisions of Central's Articles of Incorporation and the Texas Business
Corporation Act.

     (e)  Norwest shall have received approval by the Federal Reserve Board and
by such other governmental agencies as may be required by law of the
transactions

                                       28
<PAGE>
 
contemplated by this Agreement and the Merger Agreement and all waiting and
appeal periods prescribed by applicable law or regulation shall have expired.

     (f)  No court or governmental authority of competent jurisdiction shall
have issued an order restraining, enjoining or otherwise prohibiting the
consummation of the transactions contemplated by this Agreement.

     (g)  The shares of Norwest Common Stock to be delivered to the stockholders
of Central pursuant to this Agreement and the Merger Agreement shall have been
authorized for listing on the New York Stock Exchange and the Chicago Stock
Exchange.

     (h)  Central shall have received an opinion, dated the Closing Date, of
counsel to Central, substantially to the effect that, for federal income tax
purposes:  (i) the Merger will constitute a reorganization within the meaning of
Sections 368(a)(1)(A) and 368(a)(2)(E) of the Code; (ii) no gain or loss will be
recognized by the holders of Central Common Stock upon receipt of Norwest Common
Stock except for cash received in lieu of fractional shares; (iii) the basis of
the Norwest Common Stock received by the shareholders of Central will be the
same as the basis of Central Common Stock exchanged therefor; and (iv) the
holding period of the shares of Norwest Common Stock received by the
shareholders of Central will include the holding period of the Central Common
Stock, provided such shares of Central Common Stock were held as a capital asset
as of the Effective Time of the Merger.

     (i)  The Registration Statement (as amended or supplemented) shall have
become effective under the Securities Act and shall not be subject to any stop
order, and no action, suit, proceeding or investigation by the SEC to suspend
the effectiveness of the Registration Statement shall have been initiated and be
continuing, or have been threatened and be unresolved.  Norwest shall have
received all state securities law or blue sky authorizations necessary to carry
out the transactions contemplated by this Agreement.

     (j)  Prior to the mailing of the Proxy Statement referred to in paragraph
4(c), Central and the Board of Directors of Central shall have received an
opinion of Keefe, Bruyette & Woods, Inc. addressed to Central and the Board of
Directors of Central, and for their exclusive benefit, for inclusion in said
Proxy Statement and dated effective as of the date of mailing of such Proxy
Statement, based on such matters as of Keefe, Bruyette & Woods, Inc. deems
appropriate or necessary, to the effect that the consideration to be received by
stockholders of Central pursuant to the Merger is fair from a financial point of
view.  Central shall promptly provide a copy of such opinion to Norwest upon
receipt.

     7.  CONDITIONS PRECEDENT TO OBLIGATION OF NORWEST.  The obligation of
Norwest to effect the Merger shall be subject to the satisfaction at or before
the Time of Filing of the following conditions, which may be waived in writing
by Norwest:

                                       29
<PAGE>
 
     (a)  Except as they may be affected by transactions contemplated hereby and
except to the extent such representations and warranties are by their express
provisions made as of a specified date and except for activities or transactions
or events occurring after the date of this Agreement made in the ordinary course
of business and not expressly prohibited by this Agreement, the representations
and warranties contained in paragraph 2 hereof shall be true and correct in all
respects material to Central and the Central Subsidiaries taken as a whole as if
made at the Time of Filing.

     (b)  Central shall have, or shall have caused to be, performed and observed
in all material respects all covenants, agreements and conditions hereof to be
performed or observed by it at or before the Time of Filing.

     (c)  This Agreement and the Merger Agreement shall have been approved by
the affirmative vote of the holders of the percentage of the outstanding shares
of Central required for approval of a plan of merger in accordance with the
provisions of Central's Articles of Incorporation and the Texas  Business
Corporation Act.

     (d)  Norwest shall have received a favorable certificate dated as of the
Effective Date of the Merger signed by the Chairman or President and by the
Secretary or Assistant Secretary of Central, as to the matters set forth in
subparagraphs (a) through (c) of this paragraph 7.

     (e)  Norwest shall have received approval by all governmental agencies as
may be required by law of the transactions contemplated by this Agreement and
the Merger Agreement and all waiting and appeal periods prescribed by applicable
law or regulation shall have expired.  No approvals, licenses or consents
granted by any regulatory authority shall contain any condition or requirement
relating to Central or any Central Subsidiary that, in the good faith judgment
of Norwest, is unreasonably burdensome to Norwest.

     (f)  Central and each Central Subsidiary shall have obtained any and all
material consents or waivers from other parties to loan agreements, leases or
other contracts material to Central's or such subsidiary's business required for
the consummation of the Merger, and Central and each Central Subsidiary shall
have obtained any and all material permits, authorizations, consents, waivers
and approvals required for the lawful consummation by it of the Merger.

     (g)  No court or governmental authority of competent jurisdiction shall
have issued an order restraining, enjoining or otherwise prohibiting the
consummation of the transactions contemplated by this Agreement.

     (h)  The Merger shall qualify as a "pooling of interests" for accounting
purposes and Norwest shall have received from KPMG Peat Marwick LLP, as
Central's auditors and at Central's expense, an opinion to that effect.

                                       30
<PAGE>
 
     (i)  At any time since the date hereof the total number of shares of
Central Common Stock outstanding and subject to issuance upon exercise (assuming
for this purpose that phantom shares and other share-equivalents constitute
Central Common Stock) of all warrants, options, conversion rights, phantom
shares or other share-equivalents, other than any option held by Norwest, shall
not have exceeded [2,648,637].

     (j)  The Registration Statement (as amended or supplemented) shall have
become effective under the Securities Act and shall not be subject to any stop
order, and no action, suit, proceeding or investigation by the SEC to suspend
the effectiveness of the Registration Statement shall have been initiated and be
continuing, or have been threatened or be unresolved.  Norwest shall have
received all state securities law or blue sky authorizations necessary to carry
out the transactions contemplated by this Agreement.

     (k) Norwest shall have received from the Chief Executive Officer and Chief
Financial Officer of Central a letter, dated as of the effective date of the
Registration Statement and updated through the date of Closing, in form and
substance satisfactory to Norwest, to the effect that:

          (i)  the interim quarterly financial statements of Central included or
     incorporated by reference in the Registration Statement are prepared in
     accordance with generally accepted accounting principles applied on a basis
     consistent with the audited financial statements of Central;

          (ii)  the amounts reported in the interim quarterly financial
     statements of Central agree with the general ledger of Central;

          (iii)  the annual and quarterly financial statements of Central and
     the Central Subsidiaries included in, or incorporated by reference in, the
     Registration Statement comply as to form in all material respects with the
     applicable accounting requirements of the Securities Act and the published
     rules and regulations thereunder;

          (iv)  from the date of the most recent unaudited consolidated
     financial statements of Central and the Central Subsidiaries as may be
     included in the Registration Statement to a date 5 days prior to the
     effective date of the Registration Statement or 5 days prior to the
     Closing, there are no increases in long-term debt, changes in the capital
     stock or decreases in stockholders' equity of Central and the Central
     Subsidiaries, except in each case for changes, increases or decreases which
     the Registration Statement discloses have occurred or may occur or which
     are described in such letters. For the same period, there have been no
     decreases in consolidated net interest income, consolidated net interest
     income after provision for credit losses, consolidated income before income
     taxes, consolidated net income and net income per share amounts of Central
     and the Central Subsidiaries, or in income before equity in undistributed
     income of

                                       31
<PAGE>
 
     subsidiaries, in each case as compared with the comparable period of the
     preceding year, except in each case for changes, increases or decreases
     which the Registration Statement discloses have occurred or may occur or
     which are described in such letters;

          (v)  they have reviewed certain amounts, percentages, numbers of
     shares and financial information which are derived from the general
     accounting records of Central and the Central Subsidiaries, which appear in
     the Registration Statement under the certain captions to be specified by
     Norwest, and have compared certain of such amounts, percentages, numbers
     and financial information with the accounting records of Central and the
     Central Subsidiaries and have found them to be in agreement with financial
     records and analyses prepared by Central included in the annual and
     quarterly financial statements, except as disclosed in such letters.

     (l)  Central and the Central Subsidiaries considered as a whole shall not
have sustained since December 31, 1995 any material loss or interference with
their business from any civil disturbance or any fire, explosion, flood or other
calamity, whether or not covered by insurance.

     (m)  There shall be no reasonable basis for any proceeding, claim or action
of any nature seeking to impose, or that could result in the imposition on
Central or any Central Subsidiary of, any liability relating to the release of
hazardous substances as defined under any local, state or federal environmental
statute, regulation or ordinance including, without limitation, the
Comprehensive Environmental Response, Compensation and Liability Act of 1980 as
amended, which has had or could reasonably be expected to have a material
adverse effect upon Central and its subsidiaries taken as a whole.

     (n)  Since June 30, 1996, no change shall have occurred and no
circumstances shall exist which has had or might reasonably be expected to have
a material adverse effect on the financial condition, results of operations,
business of Central and the Central Subsidiaries taken as a whole (other than
changes in banking laws or regulations, or interpretations thereof, that affect
the banking industry generally or changes in the general level of interest
rates). No action taken by Central solely in order to comply with the
requirements of paragraph 4(m) hereof shall be deemed to have a material adverse
effect for purposes of this paragraph 7(n).

     8.  EMPLOYEE BENEFIT PLANS.  Each person who is an employee of Central or
any Central Subsidiary as of the Effective Date of the Merger ("Central
Employees") shall be eligible for participation in the employee welfare and
retirement plans of Norwest, as in effect from time to time, as follows:
 
     (a) Employee Welfare Benefit Plans.  Each Central Employee shall be
         -------------------------------                                
eligible for participation in the employee welfare benefit plans of Norwest
listed below subject to any eligibility requirements applicable to such plans
(and not subject to pre-existing condition exclusions, except with respect to
the Norwest Long Term Care Plan) and shall enter each

                                       32
<PAGE>
 
plan not later than the first day of the calendar quarter which begins at least
32 days after the Effective Date of the Merger (provided, however, that it is
Norwest's intent that the transition from the Central plans to the Norwest plans
be facilitated without gaps in coverage to the participants and without
duplication in costs to Norwest):
 
          Medical Plan
          Dental Plan
          Vision Plan
          Short Term Disability Plan
          Long Term Disability Plan
          Long Term Care Plan
          Flexible Benefits Plan
          Basic Group Life Insurance Plan
          Group Universal Life Insurance Plan
          Dependent Group Life Insurance Plan
          Business Travel Accident Insurance Plan
          Accidental Death and Dismemberment Plan
          Severance Pay Plan
          Vacation Program

For the purpose of determining each Central Employee's benefit for the year in
which the Merger occurs under the Norwest vacation program, vacation taken by a
Central Employee in the year in which the Merger occurs will be deducted from
the total Norwest benefit.  Central Employees shall receive credit for years of
service to Central, the Central Subsidiaries and any predecessors of the Central
Subsidiaries (to the extent credited under the vacation programs of Central and
the Central Subsidiaries) for the purpose of determining benefits under the
Norwest vacation program.

No Central Employee who is eligible to receive a separation payment, as
described on Schedule 2(i)(c), shall be eligible to participate in the Norwest
Severance Pay Plan. Central Employees who participate in the Norwest Severance
Pay Plan shall receive credit for years of service to Central, the Central
Subsidiaries and any predecessors of the Central Subsidiaries (to the extent
credited under the severance programs of Central and the Central Subsidiaries)
for the purpose of determining benefits under such plan.


     (b)  Employee Retirement Benefit Plans.
          ----------------------------------

Each Central Employee shall be eligible for participation in the Norwest
Savings-Investment Plan (the "SIP"), subject to any eligibility requirements
applicable to the SIP (with full credit for years of past service to Central and
the Central Subsidiaries for the purpose of satisfying any eligibility and
vesting periods applicable to the SIP, to the extent credited under the
respective employee retirement benefit plans of Central and the Central
Subsidiaries), and shall enter the SIP not later than the first day of the
calendar quarter which begins at least 32 days after the Effective Date of the
Merger.

                                       33
<PAGE>
 
Each Central Employee shall be eligible for participation, subject to any
applicable eligibility requirements (with full credit for years of past service
to Central and the Central Subsidiaries, to the extent credited under the
respective employee retirement benefit plans of Central and Central
Subsidiaries, for the purpose of satisfying any applicable eligibility and
vesting periods, but without credit for years of past service to Central and the
Central Subsidiaries for purposes of benefit accruals), in the Norwest Pension
Plan under the terms thereof and shall enter the Norwest Pension Plan no later
than the first day of the calendar quarter which is at least 32 days after the
Effective Date of the Merger.

     9.  TERMINATION OF AGREEMENT.

     (a)  This Agreement may be terminated at any time prior to the Time of
Filing:

          (i)  by mutual written consent of the parties hereto;

          (ii)  by either of the parties hereto upon written notice to the other
     party if the Merger shall not have been consummated byMay 31, 1997 unless
     such failure of consummation shall be due to the failure of the party
     seeking to terminate to perform or observe in all material respects the
     covenants and agreements hereof to be performed or observed by such party;
     or

          (iii)  by Central or Norwest upon written notice to the other party if
     any court or governmental authority of competent jurisdiction shall have
     issued a final order restraining, enjoining or otherwise prohibiting the
     consummation of the transactions contemplated by this Agreement; or

          (iv) by Central, within five business days after the end of the Index
     Measurement Period (as defined in subparagraph (c)(ii) below),

               (A) if both of the following conditions are satisfied:

                    (1) the Norwest Measurement Price (as defined in
               subparagraph (c)(ii) below) is less than $34; and

                    (2) the number obtained by dividing the Norwest Measurement
               Price by the closing price of Norwest Common Stock on the trading
               day immediately preceding the date of this Agreement is less than
               the number obtained by dividing the Final Index Price (as defined
               in subparagraph (c) below) by the Initial Index Price (as defined
               in subparagraph (c) below) and subtracting 0.15 from such
               quotient; or

                                       34
<PAGE>
 
               (B) if the Norwest Average Price is less than $32.  The "Norwest
          Average Price" is defined as the average of the closing prices of a
          share of Norwest Common Stock as reported on the consolidated tape of
          the New York Stock Exchange during the period of 15 trading days
          ending on the day immediately preceding the meeting of the
          shareholders of Central held to vote on this Agreement and the Merger
          Agreement.

          (v)  by either Norwest or Central upon written notice to the other
     party if the Board of Directors of Central shall in good faith determine
     that a Takeover Proposal constitutes a Superior Proposal; provided,
     however, that Central shall not be permitted to terminate this Agreement
     pursuant to this paragraph (a)(v) unless (i) it has not breached any
     covenant contained in paragraph 4(h) and (ii) it delivers to Norwest
     simultaneously with such notice of termination the fee referred to in
     paragraph 9(d) below.  As used in this Agreement;  (i) "Takeover Proposal"
     means a bona fide proposal or offer by a person to make a tender or
     exchange offer, or to engage in a merger, consolidation or other business
     combination involving Central or to acquire in any manner a substantial
     equity interest in, or all or substantially all of the assets of, Central,
     and (ii) "Superior Proposal" means a bona fide proposal or offer made by a
     person to acquire Central pursuant to a tender or exchange offer, a merger,
     consolidation or other business combination or an acquisition of all or
     substantially all of the assets of Central and the Central Subsidiaries on
     terms which the Board of Directors of Central shall determine in good
     faith, after taking into account the advice of counsel, to be more
     favorable to Central and its shareholders than the transactions
     contemplated hereby.

          (vi) by Norwest upon written notice to Central if (A) the Board of
     Directors of Central fails to recommend, withdraws, or modifies in a manner
     materially adverse to Norwest, its approval or recommendation of this
     Agreement, or the transactions contemplated hereby, (B) after an agreement
     to engage in or the occurrence of an Acquisition Event (as defined below)
     or after a third party shall have made a proposal to Central or Central 's
     shareholders to engage in an Acquisition Event, the transactions
     contemplated hereby are not approved at the meeting of Central shareholders
     contemplated by paragraph 4(c), or (C) the meeting of Central shareholders
     contemplated by paragraph 4(c) is not held prior to June 30, 1997 and
     Central has failed to comply with its obligations under paragraph 4(c).
     "Acquisition Event" means any of the following:  (i) a merger,
     consolidation or similar transaction involving Central, its intermediate
     bank holding company ("Holding Company"),  its bank subsidiary (the "Bank")
     or any successor to Central, the Holding Company or the Bank, (ii) a
     purchase, lease or other acquisition in one or a series of related
     transactions of assets of Central or any of the Central Subsidiaries
     representing 25% or more of the consolidated assets of Central and the
     Central Subsidiaries or (iii) a purchase or other acquisition (including by
     way of merger, consolidation, share exchange or any similar transaction) in
     one or a series of related transactions of beneficial ownership of

                                       35
<PAGE>
 
     securities representing 25% or more of the voting power of Central or any
     Central Subsidiary in each case with or by a person or entity other than
     Norwest or an affiliate of Norwest.

     (b)  Termination of this Agreement under this paragraph 9 shall not
release, or be construed as so releasing, either party hereto from any liability
or damage to the other party hereto arising out of the breaching party's wilful
and material breach of the warranties and representations made by it, or wilful
and material failure in performance of any of its covenants, agreements, duties
or obligations arising hereunder, and the obligations under paragraphs 4(g),
5(h) and 10 shall survive such termination.

     (c) For purposes of this paragraph 9:

          (i)  The "Company Market Capitalization" shall mean (a) the price of
     one share of the common stock of a given company at the close of the
     trading day immediately preceding the date of this Agreement multiplied by
     (b) the number of shares of common stock of such company outstanding as of
     June 30, 1996 (adjusted for any stock dividend, reclassification,
     recapitalization, exchange of shares or similar transaction between June
     30, 1996 and the close of the trading day immediately preceding the date of
     this Agreement).

          (ii) The "Index Group" shall mean all of those companies listed on
     Exhibit C the common stock of which is publicly traded and as to which
     there is, during the period of 20 trading days ending on the day
     immediately preceding the meeting of the shareholders of Central held to
     vote on this Agreement and the Merger Agreement (the "Index Measurement
     Period"), no pending publicly announced proposal for such company to be
     acquired, nor has there been any proposal by such company publicly
     announced subsequent to the day before the date of this Agreement to
     acquire another company in exchange for stock where, if the company to be
     acquired were to become a subsidiary of the acquiring company, the company
     to be acquired would be a "significant subsidiary" as defined in Rule 1-02
     of Regulation S-X promulgated by the SEC nor has there been any program
     publicly announced subsequent to the day before the date of this Agreement
     to repurchase 5% or more of the outstanding shares of such company's common
     stock.  The "Norwest Measurement Price" is  defined as the average of the
     closing prices of a share of Norwest Common Stock as reported on the
     consolidated tape of the New York Stock Exchange during the Index
     Measurement Period.

          (iii) The "Initial Index Price" shall mean the sum of the following,
     calculated for each of the companies in the Index Group:  (a) the closing
     price per share of common stock of each such company  on the trading day
     immediately preceding the date of this Agreement multiplied by (b) the
     Weighting Factor (as defined below) for each such company.

                                       36
<PAGE>
 
          (iv) The "Final Index Price" shall mean the sum of the following,
     calculated for each of the companies in the Index Group:  (a) the Final
     Price for each such company multiplied by (b) the Weighting Factor (as
     defined below) for each such company.

          (v) The "Final Price" of any company in the Index Group shall mean the
     average of the daily closing prices of a share of common stock of such
     company, as reported on the consolidated transaction reporting system for
     the market or exchange on which such common stock is principally traded,
     during the Index Measurement Period.

          (vi)  The "Total Market Capitalization" shall mean the sum of the
     Company Market Capitalization for each of the companies in the Index Group.

          (vii)  The "Weighting Factor" for any given company shall mean the
     Company Market Capitalization  for such company divided by the Total Market
     Capitalization.

     If a Common Stock Adjustment occurs with respect to the shares of Norwest
or any company in the Index Group between the date of this Agreement and the
Central shareholder meeting date, the closing prices for the common stock of
such company shall be appropriately and proportionately adjusted for the
purposes of the definitions above so as to be comparable to what the price would
have been if the record date of the Common Stock Adjustment had been immediately
following the Effective Time of the Merger.

     (d)  If this Agreement is terminated pursuant to paragraphs 9(a)(v) or
9(a)(vi),  and if terminated pursuant to paragraph 9(a)(vi) and prior thereto or
within 12 months after such termination:

          (i) Central, the Holding Company or the Bank or any successor to
     Central, the Holding Company or the Bank shall have entered into an
     agreement to engage in an Acquisition Event (as defined above) or an
     Acquisition Event shall have occurred; or

          (ii)  the Board of Directors of Central shall have authorized or
     approved an Acquisition Event or shall have publicly announced an intention
     to authorize or approve or shall have recommended that the shareholders of
     Central approve or accept any Acquisition Event,

then Central shall promptly, but in no event later than five business days after
the first of such events shall have occurred, pay Norwest a fee equal to
$3,500,000.

     (e)  If this Agreement is terminated pursuant to this paragraph 9, Norwest
shall immediately pay Central an amount equal to Central's actual expenses in
connection with

                                       37
<PAGE>
 
obtaining the environmental assessments, asbestos surveys, title commitments and
boundary surveys required by paragraphs 4(n) and 4(o) hereof.

     10.  EXPENSES. Except as otherwise provided in paragraph 9 hereof, all
expenses in connection with this Agreement and the transactions contemplated
hereby, including without limitation legal and accounting fees, incurred by
Central and Central Subsidiaries shall be borne by Central, and all such
expenses incurred by Norwest shall be borne by Norwest.

     11.  SUCCESSORS AND ASSIGNS.  This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
assigns, but shall not be assignable by either party hereto without the prior
written consent of the other party hereto.

     12.  THIRD PARTY BENEFICIARIES.  Each party hereto intends that this
Agreement shall not benefit or create any right or cause of action in or on
behalf of any person other than the parties hereto.

     13.  NOTICES.  Any notice or other communication provided for herein or
given hereunder to a party hereto shall be in writing and shall be delivered in
person or shall be mailed by first class registered or certified mail, postage
prepaid, addressed as follows:

          If to Norwest:

               Norwest Corporation
               Sixth and Marquette
               Minneapolis, Minnesota  55479-1026
               Attention:  Secretary

          If to Central:

               Central Bancorporation, Inc.
               777 West Rosedale
               Fort Worth, TX 76104
               Attention: J. Andy Thompson, Chairman & CEO

          With a copy to:

               Jenkens & Gilchrist, P.C.
               1445 Ross Avenue, Suite 3200
               Dallas, TX 75202-2799
               Attention:  Charles E. Greef, Esq.

or to such other address with respect to a party as such party shall notify the
other in writing as above provided.

                                       38
<PAGE>
 
     14.  COMPLETE AGREEMENT.  This Agreement and the Merger Agreement contain
the complete agreement between the parties hereto with respect to the Merger and
other transactions contemplated hereby and supersede all prior agreements and
understandings between the parties hereto with respect thereto.

     15.  CAPTIONS.  The captions contained in this Agreement are for
convenience of reference only and do not form a part of this Agreement.

     16.  WAIVER AND OTHER ACTION.  Either party hereto may, by a signed
writing, give any consent, take any action pursuant to paragraph 9 hereof or
otherwise, or waive any inaccuracies in the representations and warranties by
the other party and compliance by the other party with any of the covenants and
conditions herein.

     17.  AMENDMENT.  At any time before the Time of Filing, the parties hereto,
by action taken by their respective Boards of Directors or pursuant to authority
delegated by their respective Boards of Directors, may amend this Agreement;
provided, however, that no amendment after approval by the shareholders of
Central shall be made which changes in a manner adverse to such shareholders the
consideration to be provided to said shareholders pursuant to this Agreement and
the Merger Agreement.

     18.  GOVERNING LAW.  This Agreement shall be construed and enforced in
accordance with the laws of the State of Texas.

     19.  NON-SURVIVAL OF REPRESENTATIONS AND WARRANTIES.  No representation or
warranty contained in the Agreement or the Merger Agreement shall survive the
Merger or except as set forth in paragraph 9(b), the termination of this
Agreement.  Paragraph 10 shall survive the Merger.

     20.  COUNTERPARTS.  This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original but all of which shall
constitute but one instrument.


     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.


NORWEST CORPORATION             CENTRAL BANCORPORATION, INC.


By: /s/ KEN MURRAY              By: /s/ J. ANDY THOMPSON 
   --------------------------      --------------------------
Its: Executive Vice President   Its: Chairman, Chief Executive Officer
    -------------------------       ----------------------------------

                                       39
<PAGE>
 
List of exhibits and schedules to Agreement and Plan of Reorganization by and
between Norwest Corporation and Central Bancorporation, Inc. dated as of
September 16, 1996, which are not filed herewith:

       EXHIBIT      DESCRIPTION
       -------      -----------
        A           Agreement and Plan of Merger
        B           Sample Letter sent to Affiliates
        C           List of Correspondent Banks

       SCHEDULE     DESCRIPTION
       --------     -----------
        2(b)        Subsidiary Information
        2(c)        Stock Options
        2(d)        Amended and restated loan agreement with The Frost
                    National Bank, San Antonio, Texas
        2(g)        Real and Personal Property Leases
        2(h)        Taxes
        2(j)        Commitments and Contracts
        2(j) (v)    Schedule of Contracts & Agreements
        2(L)        Insurance Coverage
        2(m)        Compliance with laws
        2(o)        List of Loans to Insiders
        2(p)        Employee Benefit Plans
        4(m)        Bonuses and Deferred Compensation
        3(b)        Norwest Significant Subsidiaries
        3(h)        Norwest Tax Liabilities
        3(j)        Norwest Commitments & Contracts
        3(o)(i)     Norwest Benifit Plans
        3(o)(ii)    Norwest Benifit Plans
        3(o)(iv)    Norwest Benifit Plans
        3(o)(v)     Norwest Benifit Plans

The registrant will furnish supplementally a copy of any omitted exhibit or
schedule to the Securities and Exchange Commission upon request.

                                       40