I have specifically found a 2001 Ram 2500 with a 5.9 Cummins and a six speed manual with 179k miles..... and a long bed.
I had a '01 2500 Dodge/Cummins 235/460 3.54 gears short bed 47RE. Swapped it in for my present '03 2500 Dodge/Cummins 305/555 HO 3.73 NV5600. Much quieter much more towing power and 3-4 more mpgs.
The '01 2500 Dodge/Cummins NV5600 should be the 245/505 engine. It should accelerate like any 245 hp diesel or gas engine in a heavy pickup and pull loads at road speeds like any 505 ft lbs diesel engine.
I know its been mentioned :) but do the FASS system or a similar system to protect the VP44 pump. Spend some time on some of the Dodge/Cummins websites in the 2nd gen forums on the subject.
Those types of webs are a much better source for tech help (any diesel truck) than a RV web. Yeah, even than RV.net :B