I Have a 4x4 1997 GMC Sierra k2500, with a 5.7l Vortec. It has 170k miles, and the 4l80E transmission, also. I am contemplating having my local shop do 4.56 gears from 3.55, but thats a conversation for another day. I will probably do a 2.5" true dual exhaust as well (outside the 5k budget)...