EXHIBIT 2.1

                            DATED AS OF MAY 16, 2007

                                     BETWEEN

                           GATX FINANCIAL CORPORATION
                                    as Seller

                                       and

                       MACQUARIE AIRCRAFT LEASING LIMITED
                                    as Buyer

                        RELATING TO THE SALE AND PURCHASE

                                       of

                              THE GATX AIR BUSINESS

                                   ----------

                          SIXTH SUPPLEMENTAL AGREEMENT

                                   ----------



SIXTH SUPPLEMENTAL AGREEMENT dated as of May 16, 2007 between GATX Financial
Corporation, a Delaware corporation ("SELLER"), and Macquarie Aircraft Leasing
Limited, a company incorporated under the laws of the Republic of Ireland
("BUYER").

WITNESSETH:

WHEREAS, Seller and Buyer entered into the Sale and Purchase Agreement.

WHEREAS, Seller and Buyer entered into the First Supplemental Agreement, the
Second Supplement Agreement, the Third Supplemental Agreement, the Fourth
Supplemental Agreement and the Fifth Supplemental Agreement amending the Sale
and Purchase Agreement and agreeing certain additional matters.

WHEREAS, Seller and Buyer wish to make a certain further amendment to the Sale
and Purchase Agreement.

Accordingly, for good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, Seller and Buyer agree as follows:

1.   DEFINITIONS

1.1  Definitions

     As used in this Sixth Supplemental Agreement (including the recitals
     hereto) and save as otherwise defined herein, terms defined in the Sale and
     Purchase Agreement shall bear the same respective meanings ascribed to them
     in the Sale and Purchase Agreement when used in this Sixth Supplemental
     Agreement and:

     "FIRST SUPPLEMENTAL AGREEMENT" means the Supplemental Agreement dated as of
     November 30, 2006 between Seller and Buyer amending and supplementing the
     Sale and Purchase Agreement;

     "SECOND SUPPLEMENTAL AGREEMENT" means the Supplemental Agreement dated as
     of 17 January 2007 between Seller and Buyer amending and supplementing the
     Sale and Purchase Agreement;

     "THIRD SUPPLEMENTAL AGREEMENT" means the Supplemental Agreement dated as of
     29 January 2007 between Seller and Buyer amending and supplementing the
     Sale and Purchase Agreement;

     "FOURTH SUPPLEMENTAL AGREEMENT" means the Supplemental Agreement dated as
     of 31 January 2007 between Seller and Buyer amending and supplementing the
     Sale and Purchase Agreement;



     "FIFTH SUPPLEMENTAL AGREEMENT" means the Supplemental Agreement dated as of
     6 February 2007 between Seller and Buyer amending and supplementing the
     Sale and Purchase Agreement; and

     "SALE AND PURCHASE AGREEMENT" means the Sale and Purchase Agreement dated
     as of September 28, 2006 between Seller and Buyer.

1.2  Other Definitional and Interpretative Provisions

     Clause 1.2 of the Sale and Purchase Agreement is hereby deemed to be
     incorporated herein as if all references therein to "this Agreement" were
     references to this Sixth Supplemental Agreement.

2.   AMENDMENT

     The Sale and Purchase Agreement is amended as follows: the expression
     "thirty (30)" which appears in the second sentence of Clause 2.9.1 is
     deleted and replaced with the expression "seventy-five (75)".

3.   MISCELLANEOUS

3.1  The provisions of Clauses 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.8 and
     13.10 are hereby deemed to be incorporated herein as if all references
     therein to "this Agreement" were references to this Sixth Supplemental
     Agreement.

3.2  References to "this Agreement" in the Sale and Purchase Agreement are
     deemed to be references to the Sale and Purchase Agreement as amended by
     this Sixth Supplemental Agreement.



IN WITNESS WHEREOF, the parties to this Sixth Supplemental Agreement have caused
this Sixth Supplemental Agreement to be duly executed by their respective
authorized officers of the day and year first above written.

Seller

GATX FINANCIAL CORPORATION


By:
    ---------------------------------
Name: Robert C. Lyons
Title: Vice President and Chief
       Financial Officer


Buyer

MACQUARIE AIRCRAFT LEASING LIMITED


By:
    ---------------------------------
Name: Stephen W. Cook
Title: Director