Look for a 3500HD for your trailer - try to get the service records if you can. Once you get it - change all of the fluids to give you a "fresh start" on the truck maint. (engine oil, tranny fluid and filters - only external on an Allison, front and rear diff and transfer case, engine coolant, grease all fittings)
Duramax - Allison - - 2006 or 2007 - good tranny/engine and less emmision's.
I own a Duramax because of the Allison tranny.
My previous DAs:
2005 Chevy Silverado 3500 LT CCLB LLY SRW 4X4
2004 GMC Sierra 2500HD SE ECLB LB7 4X4
