I have some questions if anyone would care to take the time to answer them. My 79 k5 building basically from scratch now has brand new 350 motor goes to origonal 350 turbo and np203, and the same 10 bolt front 12 bolt rear from factory with 3.18 gears. Interior stripped and bedlined. I will be running 37" goodyear mt's on 16.5 6 lug wheels ( those wheels are hard to find btw I have the tires but have yet to get the wheels). My question is are 4.56 gears to much for this truck to run 65-70 hwy are are they just right (has anyone tried). All my calculations tell me i am looking at running 2700 rpm and 65 on the hwy with 4.56 gears that seems a little high. I can drop this to 2450-2500 rpm with 4.11 gears, but how much will my low end power suffer? I am building it for some serious trials but i have radial tires for a reason i will have this on the street too, and that means long drives to the trails using the hwy. I know it's been asked before and answered but a few more opinions make all the difference.