Are they the same? I have an '87 IROC. When I jack it up and put it in nuetral and hand turn the right rear tire the left tire also spins forward. I could have sworn the last 305TPI I had with rear disc the other wheel would spin in the opposite direction when I did that. The one thing I noticed with this current car is that when I try to make a U-turn the rear tire on the inside of the turn chirps due to binding. It is similar to my Bronco on dry pavement when in 4X4 mode. All the sources say my L98 350TPI car should have limited slip. But I can tell you the rear tires always turn at the same rate. Maybe someone added a truetrac to limited slip. My question is, Do I have posi or limited slip? Would limited with a truetrac act like posi?
Most cars when turning, the inside wheel has the ability to slow down to help the car turn without pushing the front wheels through a differential. Mine does not. Its not good for handling but its great for launches as I never get the one wheel spin.

 

Posi (AKA Positraction-Chevolet trade name in the 60') and a LIMITED SLIP are one and the Same. Posi is a shortened name for Limited Slip.

 

Cool. Thats what I was hoping to hear. That limited slip was the same as posi.