what size tires are you running and what transmission? also you have to change the gear in your t-case for the speedo to match your tire size as well as gears, Quadratec has 2 styles available, some t-case have long shaft gears and some have short shaft gears. i have a 94 4.0 (quite hopped up) and am running 4.56 and lockers front and rear with the NV4500 transmission, and love it! i can pull the tires off the ground from a dead stop with hardly any gas! the torque is awesome, and I have no problem doing 90+ in 5th gear down the highway