not posting to be macho,but realistically speaking,i have no power brakes or steering,my tube chassis chevelle is 2800 w/o me,16x33 m/t e/t streets skinnies up front with spool.ive driven it on street time to time and must say its not as horrible as everyone says!!!your power level dictates your choice.if you have 600 or more ft/torque id probably say spool it if you can get your tire to hook up.especially if its a heavy car.if its around the 600 or less would be fine on a locker.posi trac rears are the weakest of the 3 kinds of rear diff. in my post.