UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 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): December 10, 2004

GATX Corporation

(Exact name of registrant as specified in its charter)

New York
(State or other jurisdiction of
incorporation) 1-2328
(Commission File
Number) 36-1124040
(IRS Employer
Identification No.)

500 West Monroe Street
Chicago, Illinois
(Address of principal executive offices) 60661-3676
(Zip Code)

Registrant’s telephone number, including area code (312) 621-6200

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a- 12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01.   Other Events.

     On December 10, 2004, GATX Corporation completed the sale of its real property on Staten Island. A copy of the Press Release dated December 16 announcing the sale is attached hereto as Exhibit 99.1.

Item 9.01.   Financial Statements and Exhibits.

(a)	Financial statements of businesses acquired.
	Not applicable.
(b)	Pro Forma Financial Information.
	Not applicable
(c)	Exhibits
	See Exhibit Index included herewith.

SIGNATURE

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, thereunto duly authorized.

	GATX CORPORATION (Registrant)
	/s/ Robert C. Lyons Robert C. Lyons Vice-President, Chief Financial Officer (Duly Authorized Officer)
Date: December 16, 2004

EXHIBIT INDEX

Exhibit No.	Description
99.1	Press Release of GATX Corporation, dated December 16, 2004 reporting that it completed the sale of its property on Staten Island.