Recommendations..new truck/conversion

[SmithK]

Well I am in a debate, I currently have a 1994 Chevy CC Dually with the 6.5 TD. Well I realize I need a bit more pulling power. I look at my options: 1. Do a cummins repower with a 12V and put in a manual transmission in the process. 2. Just say screw it and get a 2003-2005 Dodge Quad Cab.
For starters the truck will be used to tow a 36 ft enclosed trailer weighing around 14k. Most of the time when towing I will be on the interstate until I get to my destination. I live in eastern TN and I travel all over so hills will be seen frequently. I like the space of my current truck and from what I have seen the Dodge is a bit smaller in the cab but think the wheel base is shorter and might help me make a few more corners. I was looking for performance numbers for the stock cummins in all years but never found a list, I did a search for performance figures but that didn't turn up anything. If I go the 12V way I would put a plate in it and a few other modifications to get the power I would want. If I just got a new truck then I would probably keep it stock ( I only need enough power for the hills and to maintain the speed limit, I am not trying to run 90mph). I would get the 6 speed manual but where I get confused is the year differences between 2003 and 2005. They seemingly up'ed the HP and TQ mid 2004. How significant a change is this and if I got the need to put a aftermarket programer on either one would they end up about the same (I hear this is a pretty cheap fast upgrade if my heart desired). If I do go the newer truck route what are some things to look for in the 2003-2005 years (incase anyone is wondering this is the body style I like and somewhat affordable with not too too many miles yet).