i have had several of these trucks and i currently mud race an 82 chev k1500, mild big block 150 shot nitrous. these trucks will handle huge power in relatively stock form. t400 trans is highly recommended as are 3/4 axles and a 205 tcase. other what are your plans, street or off road and how big of tires? i street drove the last truck with a stock 454 4spd standard and 3.07 gears and got 14mpg all the time. if you are off roading i highly recommend lower gears.my current rig has 35" boggers and 5.13 gears but it is a trailer queen and does not see any road.