SEC Form 3

FORM 3

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

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1. Name and Address of Reporting Person* ONEX CORP (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 03/14/2012	3. Issuer Name and Ticker or Trading Symbol Allison Transmission Holdings Inc [ ALSN ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	90,356,249	I	See Footnotes(1)(2)(3)(4)(5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* ONEX CORP (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* SCHWARTZ GERALD W (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Onex American Holdings II LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Onex American Holdings GP LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Allison Executive Investco LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Allison Executive Investco II LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Onex American Holdings Subco LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* OAH Wind LLC (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Onex Allison Holding Ltd S.A.R.L. (Last) (First) (Middle) C/O ONEX CORPORATION 161 BAY STREET (Street) TORONTO A6 M5J 2S1 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Includes: (i) 40,849,245 shares of common stock held by Onex Partners II LP; (ii) 25,949,370 shares of common stock held by Onex American Holdings II LLC; (iii) 383,940 shares of common stock held by Onex Partners II GP LP; (iv) 769,558 shares of common stock held by Onex US Principals LP; (v) 19,256,250 shares of common stock held by Onex Allison Co-Invest LP; and (vi) 1,513,297 shares of common stock held by Allison Executive Investco LLC.

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 American Holdings II LLC, through Onex Corporation's ownership of all of the equity of Onex American Holdings II LLC, (c) 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, (continued)

3. (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, (e) 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, and (f) Allison Executive Investco LLC, through Onex Corporation's ownership of all of the equity of Onex American Holdings II LLC, which owns all of the equity of Allison Executive Investco LLC.

4. Also includes 1,633,404 shares of common stock and 1,185 shares of non-voting common stock held by Onex Advisor III LLC, 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 own beneficially all of the common stock and non-voting common stock owned beneficially by Onex Corporation. Mr. Schwartz disclaims such beneficial ownership, except to the extent of his pecuniary interest therein. Mr. Schwartz has indirect voting and investment control of Onex Corporation.

5. Due to the limitations of the electronic filing system, Onex Partners LLC, Onex US Principals LP, Onex Partners GP Inc., Onex Partners II GP LP, Onex Allison Co-Invest LP, Onex Partners II LP, 1597257 Ontario Inc., Onex Advisor III LLC and Onex Advisor Subco LLC are filing a separate Form 3.

Remarks:

Exhibit List: Exhibit 99 - Joint Filer Information

	/s/ Christopher Govan, Authorized Person	03/14/2012
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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