honestly i wouldnt use a T56 in stock spec'd at all for what you want. they are only rated at 400lbft TQ. yes you can have a modded one like mine which is good for 700hp but was also 34xx dollars thats no clutch, no shifter

also using the T56 you need a Ls1 starter,LS6 slave, LS1 style clutch.. and a stock clutch wont hold and the LS clutches are rated at roughly 3500lbs of vehicle weight.

im fighting clutch issues cause of my weight, just hink what your heavier truck is going to do