EX-10.28



 Exhibit 10.28 

FIRST AMENDMENT TO THE STOCKHOLDERS AGREEMENT 
 This FIRST AMENDMENT TO THE STOCKHOLDERS AGREEMENT, dated as of May 8, 2013 (this “Amendment”), is made by and among Allison Transmission Holdings, Inc., a Delaware corporation, and
each of the other signatories hereto. 
 W I T N E S S E T H: 

WHEREAS, the parties hereto have entered into that certain Amended and Restated Stockholders Agreement, dated as of March 12, 2012
(the “Stockholders Agreement”); 
 WHEREAS, Section 8.8(a) of the Stockholders Agreement provides that the
parties hereto may amend the Stockholders Agreement; and 
 WHEREAS, the parties hereto desire to amend the Stockholders
Agreement as set forth herein. 
 NOW, THEREFORE, in consideration of the foregoing and the mutual covenants and agreements
herein contained and other good and valuable consideration, the receipt, adequacy and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows: 
 Section 1. Amendment to the Stockholders Agreement. The definition of “Restricted Management Stockholders” provided in Section 1.1 of the Stockholders Agreement is hereby
amended and restated in its entirety to read as follows: 
 “Restricted Management Stockholders” shall mean
Lawrence E. Dewey, David S. Graziosi, Michael G. Headly, Randall R. Kirk and David L. Parish. 
 Section 2.
Effectiveness of Amendment. Upon the execution and delivery hereof, the Stockholders Agreement shall thereupon be deemed to be amended and restated as hereinabove set forth as fully and with the same effect as if the amendment and restatement
made hereby was originally set forth in the Stockholders Agreement, and this Amendment and the Stockholders Agreement shall henceforth respectively be read, taken and construed as one and the same instrument. 

Section 3. General Provisions. 
 (a) Miscellaneous. This Amendment may be executed in one or more counterparts, all of which shall be considered one and the same agreement and shall become effective when one or more counterparts
have been signed by each of the parties hereto and delivered to the other parties hereto. This Amendment shall be governed by, construed, applied and enforced in accordance with the internal laws of the State of Delaware. 







 (b) Stockholders Agreement in Effect. Except as specifically provided for in this
Amendment, the Stockholders Agreement shall remain unmodified and in full force and effect. 
 First Amendment to Stockholders
Agreement 







 IN WITNESS WHEREOF, each of the parties hereto has caused this Amendment to be executed as
of the date first written above. 
  

			
	ALLISON TRANSMISSION HOLDINGS, INC.
		
	By: 	 	/s/ Lawrence E. Dewey
	 Name: Lawrence E. Dewey
 Title:   President and Chief Executive Officer



  

			
	 CARLYLE PARTNERS IV AT HOLDINGS, L.P.
 By: TC Group IV Managing GP, L.L.C., its general partner

		
	By: 	 	/s/ Brian A. Bernasek
	 Name: Brian A. Bernasek
 Title:   Authorized Person



  

			
	 ONEX ALLISON CO-INVEST LP
 By: Onex Partners II GP LP, its general partner
 By: Onex Partners Manager LP, its agent

By: Onex Partners Manager GP ULC, its general partner

		
	By: 	 	/s/ Robert M. Le Blanc
	 Name: Robert M. Le Blanc
 Title:   Senior Managing Director

		
	By: 	 	/s/ Donald F. West
	 Name: Donald F. West

Title:   Vice President and Secretary



  

			
	ONEX ALLISON HOLDING LIMITED S.Á R.L.
		
	By: 	 	/s/ Donald F. West
	 Name: Donald F. West

Title:   Type A Manager

		
	By: 	 	/s/ Olivier Dorier
	 Name: Olivier Dorier

Title:   Type B Manager



 First Amendment to Stockholders Agreement 







 
			
	 ONEX PARTNERS II GP LP
  

By: Onex Partners GP Inc., its general partner

		
	By: 	 	/s/ Robert M. Le Blanc
	 Name: Robert M. Le Blanc
 Title:   President

		
	By: 	 	/s/ Donald F. West
	 Name: Donald F. West

Title:   Vice President



  

			
	 ONEX PARTNERS II LP
 By: Onex Partners II GP LP, its general partner
 By: Onex Partners Manager LP, its agent

By: Onex Partners Manager GP ULC, its general partner

		
	By: 	 	/s/ Robert M. Le Blanc
	 Name: Robert M. Le Blanc
 Title:   Senior Managing Director

		
	By: 	 	/s/ Donald F. West
	 Name: Donald F. West

Title:   Vice President and Secretary



  

			
	ONEX US PRINCIPALS LP
		
	By: 	 	/s/ Donald F. West
	 Name: Donald F. West

Title:   Representative of the General Partner



  

			
	1597257 ONTARIO INC.
		
	By: 	 	/s/ Christopher A. Govan
	 Name: Christopher A. Govan
 Title:   Managing Director

		
	By: 	 	/s/ Andrea E. Daly
	 Name: Andrea E. Daly

Title:   Vice President and General Counsel



 First Amendment to Stockholders Agreement