I found out a few days ago that I have a posi-trac in my rear, and I'm wondering if that's factory or not. She's a 92 RS, but it's a B4C, so it's basically a Z28. 350 TPI, 4L60 trans.

 

yes they did come fromthe factory with them

 

PosiTrac = limited slip= spin resistant diff. all the same stuff, until you get into lockers do they differ....same function, different way of achieving it. But otherwise ......if you have a tag saying "spin resistant diff" you have a posi, or a limited slip in non chevy terms.

 

Look for G80 on your RPO label, if it's there, it's a factory posi.

 

Wow. Thanks for the help.

 

Lockers and 1 axle diffs are entirely different in design from standard posi. That's why posi is the only one called limited slip as it can still slip under high torque situations.