I've burnt rubber before and only one tire spun. I spun them today and both wheels spun Does posi only kick in sometimes or is it suppose to always work? I want to know because if my car doesn't have posi then I'm going to install it.

Well, jack the rear of your car up so both rear wheels are off the ground. Put the tranny in (N) and spin the R/R tire foward. If your diff. is a posi both tires will spin in the same direction. If not one will spin foward and one will spin backward.

Auggie

Thanks, I'll try that as soon as I can.