4.10\'s or 4.56 gears? I have a 85 K10 shortbed with 4" of lift, 350 with headers and dual 2 1/4" exhaust with 800cfm Q-Jet, aluminum intake (soon to be a Weiand) and will also have a cam in it to match the gears. Also has a 700r4 and 33x12.5" tires. I'm thinking going with 4.10s would be good and that would put my cruise at 70mph right around 2k and my cruise rpm in 3rd around 2900-3000 for towing. I use this truck for towing a single axle trailer with 4 motorcycles, 1 4-wheeler, and some other small stuff and sometimes a lawn mower. I figure the 3k rpm cruise speed while towing would be good rpm and i'll get a cam that gives good power for that rpm also. And sometime in the future it will be getting a 406, so torque will be of no concern by then. It also tows a 18' tri-hull boat with a Chevy 250 I6 in it.