I had an 01 6.0 2500 chevy that was lifted, and it was cool and all, but full load over the grape vine ore any decent grade is a slow go in a gas jobber. Especially if they are lifted then they loose even more power. Get a diesel any diesel, You want to be the guy going 75 out of Indio not 40mph. My 04 duramax gets 20 mpg consistently, and my 83gmc cummins gets 15mpg. Gas motors are for jet boats, Diesels are for trucks.