If you are looking at a Cummins powered Dodge, take the time to read through the linked file. It will get you up to speed quickly on the good/bad/ugly of the Dodge/Cummins.
http://www.turbodieselregister.com/i...sGuide2010.pdf
I recently turned 241,000 in my 97 and last night filled up with fuel. Mileage worked out to 19.3 mpg (done the old fashion way by hand) in combined driving and that's winter fuel with cold a$$ temps. There isn't a gas powered 3/4 ton 4x4 extra cab LWB truck out there that could compete with that, period.
There are weak points on the Dodge/Cummins package, but with some attention to detail and preventative maintenance, you should have a good reliable truck for many years.
Once you get used to driving a diesel powered truck, you'll never consider anything less.
Good Luck
Chris