Washington, D.C.

                                    FORM 8-K

                                 CURRENT REPORT

     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

         Date of Report (Date of earliest event reported): June 23, 2004

                                   AAON, INC.
             (Exact name of registrant as specified in its charter)

           Nevada                       0-18953                  87-0448736
           ------                       -------                  ----------
(State or other jurisdiction          (Commission               (IRS Employer
      of incorporation)               File Number)           Identification No.)

                     2425 South Yukon, Tulsa, Oklahoma 74107
                    (Address of principal executive offices)

       Registrant's telephone number, including area code: (918) 583-2266

Item 4.  Changes in Registrant's Certifying Accountant.

         At a meeting on June 22, 2004, the Audit Committee of the Board of
Directors of the Company approved the engagement of Grant Thornton LLP as its
independent auditors to replace the firm of Ernst & Young LLP which was
dismissed as auditors of the Company effective June 23, 2004.

         The reports of Ernst & Young LLP on the Company's financial statements
for the past two fiscal years did not contain an adverse opinion or a disclaimer
of opinion and were not qualified or modified as to uncertainty, audit scope or
accounting principles.

         In connection with the audits of the Company's financial statements for
the fiscal years ended December 31, 2002 and 2003, and in the subsequent interim
period, there were no disagreements with Ernst & Young LLP on any matter of
accounting principles or practices, financial statements disclosure or auditing
scope or procedure which, if not resolved to the satisfaction of Ernst & Young
LLP, would have caused Ernst & Young LLP to make reference to the matter in its
report. The Company has requested Ernst & Young LLP to furnish a letter
addressed to the Commission stating whether it agrees with the above statements.
A copy of that letter, dated June 25, 2004, is filed as Exhibit 1 to this Form


         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                         AAON, INC.

Date:  June 25, 2004                     By: /s/ John B. Johnson, Jr.
                                                 John B. Johnson, Jr., Secretary


                                    Exhibit 1

June 25, 2004

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549


We have read Item 4 of Form 8-K dated June 25, 2004, of AAON, Inc. and are in
agreement with the statements contained in the second and third paragraphs on
page one therein. We have no basis to agree or disagree with other statements of
the registrant contained therein.

                                                   /s/ Ernst & Young LLP