My car has been having problems with traction; it spins the tires really easy and it did not do this when I first installed the new used 3.42 geared stock posi rear end. So today I decided to hold my foot on the break and press the throttle, I only got the passenger side tire to spin. If the posi were working correctly it should spin both tires; this must mean my posi unit is broken. How much will a stock posi unit run me and how difficult is it to install? Do I need to measure the play in the rear and add shims according to the play, or can I just bolt the new unit in? Thanks

 

Maybe it means one of your rear brakes is holding better than the other one.

When you just floor it (not playing with the brakes), and the tires break loose, how many stripes of rubber do you leave - 1 or 2?

 

I am only leaving one stripe of rubber. And it feels like the car wants to go sideways when I floor it. It sucks, the car felt faster when it used to hook up with the posi unit working. I used royal purple, it said it had limited slip additive so I did not use the GM limited slip additive; could this cause my problem?