Sec Form 4 Filing - ONEX CORP @ Allison Transmission Holdings Inc - 2014-02-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ONEX CORP 2. Issuer Name and Ticker or Trading Symbol Allison Transmission Holdings Inc [ ALSN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 161 BAY STREET, 3. Date of Earliest Transaction (MM/DD/YY) 02/28/2014 (Street) TORONTO, A6M5J 2S1 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/28/2014 S 14,375,000 D $ 29.17 35,321,249 I See footnotes ( 1 ) ( 2 ) ( 3 ) ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ONEX CORP 161 BAY STREET TORONTO, A6M5J 2S1 X SCHWARTZ GERALD W C/O ONEX CORPORATION 161 BAY STREET TORONTO, A6M5J 2S1 X Onex American Holdings II LLC 421 LEADER STREET MARION, OH43302 X Onex American Holdings GP LLC 421 LEADER STREET MARION, OH43302 X Allison Executive Investco LLC 421 LEADER STREET MARION, OH43302 X Allison Executive Investco II LLC 421 LEADER STREET MARION, OH43302 X Onex American Holdings Subco LLC 421 LEADER STREET MARION, OH43302 X OAH Wind LLC 421 LEADER STREET MARION, OH43302 X Onex Allison Holding Ltd S.A.R.L. 421 LEADER STREET MARION, OH43302 X Signatures ONEX CORPORATION, By: /s/ Andrea E. Daly, Authorized Person 03/04/2014 Signature of Reporting Person Date /s/ Donald W. Lewtas, attorney-in-fact 03/04/2014 Signature of Reporting Person Date ONEX AMERICAN HOLDINGS II LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date ONEX AMERICAN HOLDINGS GP LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date ALLISON EXECUTIVE INVESTCO LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date ALLISON EXECUTIVE INVESTCO II LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date ONEX AMERICAN HOLDINGS SUBCO LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date OAH WIND LLC, By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date ONEX ALLISON HOLDING LIMITED S.a R.L., By: /s/ Donald F. West, Authorized Person 03/04/2014 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Following the reported transaction, includes: (i) 15,968,418 shares of common stock held by Onex Partners II LP; (ii) 10,735,459 shares of common stock held by Onex Allison Holding Limited S.a R.L.; (iii) 7,527,479 shares of common stock held by Onex Allison Co-Invest LP; (iv) 300,828 shares of common stock held by Onex US Principals LP; and (v) 150,086 shares of common stock held by Onex Partners II GP LP. ( 2 )Onex Corporation may be deemed to beneficially own the common stock held by (a) Onex Partners II LP, through Onex Corporation's ownership of all of the common stock of Onex Partners GP Inc., the general partner of Onex Partners II GP LP, the general partner of Onex Partners II LP; (b) Onex Allison Holding Limited S.a R.L., through Onex Corporation's ownership of all of the equity of Onex American Holdings II LLC, which owns all of the equity of each of Allison Executive Investco LLC, which owns all of the equity of Allison Executive Investco II LLC, and Onex American Holdings Subco LLC, which owns all of the equity interests of OAH Wind LLC, which OAH Wind LLC and Allison Executive Investco II LLC own all of the equity interests of Onex Allison Holding Limited S.a R.L.; (continued) ( 3 )(c) Onex Allison Co-Invest LP, through Onex Corporation's ownership of all of the common stock of Onex Partners GP Inc., the general partner of Onex Partners II GP LP, the general partner of Onex Allison Co-Invest LP; (d) Onex US Principals LP, through Onex Corporation's ownership of all of the equity of Onex American Holdings II LLC, which owns all of the equity of Onex American Holdings GP LLC, the general partner of Onex US Principals LP; and (e) Onex Partners II GP LP, through Onex Corporation's ownership of all of the common stock of Onex Partners GP Inc., the general partner of Onex Partners II GP LP. ( 4 )New PCo II Investments Ltd. is the record holder of 637,794 shares of common stock and 1,185 shares of non-voting common stock. 1597257 Ontario Inc., the sole shareholder of New PCo II Investments Ltd., is an independent entity that is controlled by Mr. Gerald W. Schwartz. Mr. Schwartz, the Chairman, President and Chief Executive Officer of Onex Corporation, owns shares representing a majority of the voting rights of the shares of Onex Corporation and as such may be deemed to beneficially own all of the common stock owned beneficially by Onex Corporation. Mr. Schwartz disclaims any such beneficial ownership. Mr. Schwartz has indirect voting and investment control of Onex Corporation.

Remarks: Due to the limitations of the electronic filing system, Onex Partners GP Inc., Onex US Principals LP, Onex Partners II GP LP, Onex Allison Co-Invest LP, Onex Partners II LP, 1597257 Ontario Inc. and New PCo II Investments Ltd. are filing a separate Form 4.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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