EXHIBIT 32

                        GATX CORPORATION AND SUBSIDIARIES

                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

    CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO
                 SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

            In connection with the Quarterly Report of GATX Corporation (the
"Company") on Form 10-Q for the period ending September 30, 2004, as filed with
the Securities and Exchange Commission on the date hereof (the "Report"), each
of the undersigned officers of the Company, certify, pursuant to 18 U.S.C.
Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of
2002, that:

            (1) The Report fully complies with the requirements of section 13(a)
      or 15(d) of the Securities Exchange Act of 1934; and

            (2) The information contained in the Report fairly presents, in all
      material respects, the financial condition and results of operations of
      the Company.

            /s/ Ronald H. Zech                       /s/ Brian A. Kenney
- --------------------------------------     ------------------------------------
             Ronald H. Zech                             Brian A. Kenney
              Chairman and                               President and
        Chief Executive Officer                      Chief Financial Officer

November 8, 2004

            This certification accompanies the Report pursuant to section 906 of
the Sarbanes-Oxley Act of 2002 and shall not be deemed filed by GATX Corporation
for purposes of section 18 of the Securities Exchange Act of 1934, as amended.

            A signed original of this written statement required by Section 906
has been provided to GATX Corporation and will be retained by GATX Corporation
and furnished to the Securities and Exchange Commission or its staff upon
request.