I'd recommend a Large Steam Tsunami.
http://www.soundtraxx.com/products/dcc/tsunamisound.htm
Bachmann actually uses a specialized tsunami in their DCC & Sound on board locos. No modifications need to be made to the Tsunami to put it in your 2-10-2, the Bachmann one is only different in the amount of sounds on the decoder--the stock Tsunami has more.
http://www.soundtraxx.com/products/dcc/tsunamisound.htm
Bachmann actually uses a specialized tsunami in their DCC & Sound on board locos. No modifications need to be made to the Tsunami to put it in your 2-10-2, the Bachmann one is only different in the amount of sounds on the decoder--the stock Tsunami has more.