i have a 1981 with the L-82 i went bracket racing with it last night and as the track stay warm the car hooked up but as it cooled down it started to slip so I want to run some slick for me to do that what do i need to do to the rearend to hold the power with out snaping the half shaft

 

You should post your times. What were your RT and 60 foot times? How about trap speeds? These will tell you a lot on how to improve your runs. As far as snapping a half shaft, that's the risk you pay when you don't have a solid axel. I would actually try some traction bars; four link or slappers. All depends on how much you want to invest in running drag races. Next time you race go ask the Terminator (03-04 Mustang Cobra) guys what they are doing for traction. Those guys are always breaking output shafts.