Hey guys...

I have an '83 Z28 with 3.73 gears (factory), 5 speed and a 350. My problem is that either my posi is dead or i never had one to begin with. Not entirely sure right now because the old owner kinda thrashed the car, so it could be either and i can't find my RPO sheet anywere.

Anyway, enough with my rambling.... If i don't have a posi in my axle, can i install one using the other existing parts (ie. ring and pinion) and if it there, but dead, can it be rebuilt or does it have to be replaced?

Thanks.

 

yes....

 

yes, only thing to watch is spline count on the axles, you should have 26 spline so the new carrier would need to be 26 or you'd need to swap axles for a 28 spline carrier.

 

Ok, that makes sense... so if i got posi hunting, it does have to be out of the same type of axle, right? I'd have to find one in a 9 bolt to use in my 9 bolt axle?

 

Count your bolts. I'd bet you have a 10-bolt. 9-bolts weren't introduced until 85. No such thing as "features from the future"!!

Posi wasn't too common in the older cars, nor were rear disk brakes. There's a good chance yours wasn't a posi, especially if it has drums.

RPO sheets usually aren't in cars that old; they didn't start leaving a copy of that until some years later.

I can't believe you're telling us that, and haven't even changed the fluid. Tomorrow, while you're doing that bit of long-overdue maintenance, which requires taking the cover off, make a point of looking at it to see if it has a posi in it.

Yes, and yes.

Avoid the ones in S trucks, affectionately known as the Eaton "Grenade Lock".

 

yeah i do believe a 3.73 rear end from a 83 z28 would be a 10 bolt.

good luck in your search for a posi.

 

The fluid was changed when i got it 8 months ago. My dad did that, but he doesn't remember if it had a posi (go figure, lol)

and yea, i knew it was either a 9 or 10 bolt, just couldn't remember (off day today, lol)

And when i have a chance, i'll check out some other f-bodies at the wrecker for a posi. They have lots of early 3rd gens there for some reason.