well i thought i had posi, because the first day i had my car, i did a break torque, and both tires let loose....and usually everytime i just do a regular burnout, they both spin....but lately, when i do a break torque, only 1 wheel spins...Then a friend of mine told me to jack it up, and spin 1 tire forward, and the other one should spin forward too if i have posi....but the other one spun backwards when i spune one forward....So do i have posi or what? I was thinking just limited slip, but i dunno, can somebody clue me in here...thanx...

 

If two tires used to spin, and now only one spins, it sounds like you HAD a posi The older units incorporated clutches for torque biasing and they're known for wearing out. Especially after a nice power upgrade like an L98 with bolt-ons

If the unit is worn out, the spin the tire or driveshaft method may or may not work. Look in your center console for your RPO codes. G80 means the car was factory optioned with a limited slip. However, the only true way too tell would be to open the rear diff and look.

Edit: BTW, posi, positraction, limited slip, trak-lok, etc are all the same thing.