my 08 1 ton mega cab with the 6.7 diesel and the 68rfe 6 speed tranny. 2x4 with single rear tires and a 3.73 gear in the back. pulling a 32 foot trailer. i averaged around 18 towing and over 21 empty on the highway.
the drivers seats padding was shot within 30,000 miles, it needed front brake pads at around 90,000 miles and a set of tires. ran good until it started to have erratic headlight brightness. looked like a honda goldwing. if i used high beam. found out that the wiring harness had corrosion at a junction in the frame cab area. over $2500 to fix. it required several computer updates over the 5 years i owned it.
it was a great truck, plenty of power just had lousy seats and a faulty wiring harness.