I bought this truck new and it has the 5.9 HO diesel engine. This is a great truck for pulling a trailer with a loader on it, or pulling your 20' boat to the lake. I now have 35500 miles on it and the fuel mileage keeps improving. Currently averaging 16.5 to 18 mpg at 65 mph. One thing that I would say is get a manual transmission instead of the 4-speed automatic. My last truck was a 1998 dodge 2500 that had a manual instead of the automatic and I got 2 to 3 mpg better fuel mileage. I have not had any problems with this truck and overall would recommend it to my friends.
5.9 Liter HO Cummins Engine, Manual shift on the fly 4X4, Power heated mirrors, Big Horn edition.