QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549


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): March 18, 2003

STEWART & STEVENSON SERVICES, INC.
(Exact name of registrant as specified in its charter)

Texas
(State or other jurisdiction
of incorporation)		   0-8493
(Commission
File Number)		   74-1051605
(I.R.S. Employer
Identification No.)

2707 North Loop West
Houston, Texas
(Address of principal executive offices)
 
77008
(Zip code)

Registrant's telephone number, including area code: (713) 868-7700


Item 7.    Exhibits.

Exhibit 99.1   Company Press Release dated March 17, 2003, titled "Stewart & Stevenson Announces Fiscal 2002 Fourth Quarter Earnings Release and Conference Call Schedule".


Item 9.    Regulation FD Disclosure.

        On March 17, 2003, Stewart & Stevenson Services, Inc. (the "Company") issued the press release attached hereto as Exhibit 99.1.


SIGNATURES

        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 hereto duly authorized.

    STEWART & STEVENSON SERVICES, INC.

Date: March 18, 2003
 
By:
/s/  JOHN B. SIMMONS      
Name: John B. Simmons
Title: Vice President and Chief Financial Officer


EXHIBIT INDEX

99.1
Company Press Release dated March 17, 2003, titled Stewart & Stevenson Announces Fiscal 2002 Fourth Quarter Earnings Release and Conference Call Schedule.


QuickLinks