UNITED STATES SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 4
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP
( ) Check this box if no longer subject to Section 16.
Form 4 or Form 5 obligations may continue. See Instructions 1(b).
1. Name and Address of Reporting Person
   James M. Denny
   Sears Tower, Suite 9420
233 South Wacker Drive
   IL, Chicago 60606
2. Issuer Name and Ticker or Trading Symbol
   GATX CORPORATION (GMT)

3. IRS or Social Security Number of Reporting Person (Voluntary)
   ###-##-####
4. Statement for Month/Day/Year
   5/1/2003
5. If Amendment, Date of Original (Month/Day/Year)

6. Relationship of Reporting Person(s) to Issuer (Check all applicable)
   (X) Director ( ) 10% Owner ( ) Officer (give title below) ( ) Other
   (specify below)

7. Individual or Joint/Group Filing (Check Applicable Line)
   (X) Form filed by One Reporting Person
   ( ) Form filed by More than One Reporting Person


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 Table I -- Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned                                                 |
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1. Title of Security|2.    |2A.   |3.    |4.Securities Acquired (A)         |5.Amount of        |6.Dir |7.Nature of Indirect       |
                    |Trans-|Exec- |Trans |  or Disposed of (D)              |  Securities       |ect   |  Beneficial Ownership     |
                    |action|ution |action|                                  |  Beneficially     |(D)or |                           |
                    |      |      |    | |                  | A/|           |  Owned Following  |Indir |                           |
                    |Date  | Date |Code|V|    Amount        | D |    Price  |  Reported Trans(s)|ect(I)|                           |
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Common Stock        |5/1/ 2|      |A   | |1143.3952 1       |A  |18.585     |12179.605 2        |D     |                           |
                    |003   |      |    | |                  |   |           |                   |      |                           |
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 Table II -- Derivative Securitites Acquired, Disposed of, or Beneficially Owned                                                   |
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1.Title of   |2.Con-  |3.     |3A.   |4.    |5.Number of De |6.Date Exer|7.Title and Amount  |8.Price|9.Number    |10.|11.Nature of|
  Derivative |version |Trans- |Deemed|Trans-| rivative Secu |cisable and|  of Underlying     |of Deri|of Deriva   |Dir|Indirect    |
  Security   |or Exer |action |      |action| rities Acqui  |Expiration |  Securities        |vative |tive        |ect|Beneficial  |
             |cise    |       |Execu-|      | red(A) or Dis |Date(Month/|                    |Secu   |Securities  |(D)|Ownership   |
             |Price of|       |ution |      | posed of(D)   |Day/Year)  |                    |rity   |Benefi      |or |            |
             |Deriva- |       |      |      |               |Date |Expir|                    |       |ficially    |Ind|            |
             |tive    |       |      |      |           | A/|Exer-|ation|   Title and Number |       |Owned Follow|ire|            |
             |Secu-   |(Month/|(Month|    | |           | D |cisa-|Date |   of Shares        |       |ing Reported|ct |            |
             |rity    |Day/   |/Day/ |Code|V|  Amount   |   |ble  |     |                    |       |Trans-      |(I)|            |
             |        |Year)  |Year) |    | |           |   |     |     |                    |       |action(s)   |   |            |
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             |        |       |      |    | |           |   |     |     |            |       |       |            |   |            |
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Explanation of Responses:
1. Includes that portion of (a) the quarterly payment of the annual directors'
fee (766.7474 shares) credited to an account established for each director
under the GATX Directors' Phantom Stock Plan ("Phantom Stock Plan") and (b) the
annual retainer and m
eeting fee (376.6478 shares) which the reporting person elected to invest in
units of phantom stock under the Directors' Deferred Fee Plan ("Deferred Fee
Plan"), which in each case will be settled in common stock upon the expiration
of the director's serv
2. Includes 168.3619 shares acquired pursuant to a dividend reinvestment
feature of the GATX Phantom Stock Plan and 36.1964 shares acquired pursuant to
a dividend reinvestment feature of the Deferred Fee Plan.
SIGNATURE OF REPORTING PERSON
James M. Denny
James M. Denny