I started with a 7.3L NA/5spd F250 = sucked on anything by flat level road.
Went to a 5.9L Cummins/auto D-350 = couldn't tow 65mph comfortably in OD & 3rd ran 3000rpm which got me crap mpg
Sold out to the light(?) side & bought a 3/4ton gas rig (Vortec 5.7L/4l80E) that has NO issue dragging my Jeep or hauling 7K# plus. It's cheaper to maintain & troubleshoot for the3k-5k miles it gets used each year!
Unless you're trying to jones or compensate? Just asking 
