i have a 81 silverado 3/4ton longbox 2wd that i drag race for fun. 375 hp 454, th400 stage 2 shift kit, stock converter, stock 14 bolt ff axle with 4.10 open diff, i have a 4.56 locker laying in my garage and i was wondering if that is too low for my application. my truck weighs 5000lbs and currently runs high 14s low 15s at 90+mph in the 1/4. any suggestions on this would be great!

 

If all you do is drag race it, it can't hurt to drop in those gears and locker. If you DD this truck though, going any steeper with the gears with that transmission, your mileage is going to suffer more than it does now.

 

do a converter it'll help it get out the hole and run faster. the gears are an easy upgrade but like smokeshow said...it wont be as MPG friendly even for a street toy/track toy