TomG2 - I am researching this purchase (2013/2014 2500 HD with 6.0/4.1). The fifth wheel towing capacity is rated at 14,200 or 20,500 gross so this truck should be able to pull the Montana 3400RL as far as I can tell. I assume the frame, brakes and everything else is the same as the Duramax equipped so the only issue is the engine. I may decide to give up the torque in the mountains for a cheaper price and realize it will be slower going up elevations. My mountain (west) trips will be limited in the future. We have made those trips several times already. A 3500 may be a better fit so that option is not out. But, could find a good used Duramax tomorrow. Again, this will be a SRW regardless. Thanks.