throw you a 5.9 cummins in it.
there are a few programmers for gas burners. i just pulled my 37s out from my tck and fixin to take the lift kit out. i was getting 24mpg before the lift and 12-14 with the lift and tires. im driving a 4dr 4x4 long box dodge and with just the big tires gone, i have went up to 18mpg. my aint stock though. i have a few aftermarket mods on it.