Ram tow vehicle

I have an 04.5 2500 4x4, Quad Cab, "600 Cummins".. Bought it new.. Love this truck. Zero problems.. Do your research ,the autos in these trucks are good. It was the earlier ones that are the "weak" ones. Mine only has about 115,000 miles on it. Gets about 17 MPG avg. in town and some hwy.. On the HWY over 2000 RPM your MPG will suffer. Long trips under 1700 rpm 23 mpg... Make sure one of those trucks was not a single rear wheel 3500 that could be the difference. ???