1970 Camaro rearend
 

My good friend just scored this 12-bolt COZ coded rear off Marketplace. Looks to be completely original with the dated 3.73 gearset and Eaton posi. Uncut spring perches and all correct measurements. His question, (that I cannot answer) was this specific to a Z-28, RS, or ?? Thanks for any information I can relay to him.
Dave

z and ss

I seen that.. just didnt have the time to commit

I think just Z. SS came with a 3.55 standard and option was 4.10. Z option was 4.10 too. I've never heard of a 3.73 SS.

WOW,........that's a score. Most 12 bolt Chevy rear ends are prices well over a grand,...with Camaro ones being even more. And, if that was a 1st gen piece, the price goes up.

RS is an appearance package and has nothing to do with performance, so that wouldn't matter. I would think that it would be Z28 or maybe L78.

As Dave mentioned, 3.73s was a Z28 only ratio for 1970, but the COZ code was also used in '70 T/As as they shared the same 12-bolt as the Camaro that year. Either way, that's a great score!

First off, a huge thank you to all who responded, much appreciated.
I'm going to take a swing at this, as my friend is a "as-is" flipper and it will be for sale. I'm looking at it first hand today. I enjoy restoration projects and reuniting rare parts with appropriate applications. I'll let ya'll know if I'm successful, he's a tough negotiator.

Dave

$250 for that is an ABSOLUTE smoking deal - the caliber of a deal that I'd wager only a select few of us might get - Congrats!

I have understood that the Camaro could have a four leaf spring, which determined different perches vs the Firebird which always used three leaf springs (and the shorter perches) - I do not know if the differential housing code changed with the different perches.

This rear was the "performance" ratio offered for the '70 Trans Am and Formula 400;
For the Firebird line this ratio was only available with a posi;
For the Trans Am a posi was standard;
For the Formula posi was a required option with this gear set;
For the both models this gear set could be ordered with the automatic (M40), wide ratio four speed (M20), close ratio (M21; was a required option; M22 not offered).

I hope some of this yammering helps someone. ;)

ss l78 and 350 got the 12 bolt

I thought a 12 bolt came in any 1970 Camaro with any engine that had a 4bbl, but the 3:73
ratio was standard on the Z-28 with the 4:10 optional. I do not know about the L-78 in 1970,
so my vote is it came out a 1970 Z-28.

Bill

Correct Bill...only the Z28 could have gotten the 3.73s. L78s were 3.55 std and 4.10 optional.

70 Z , T/A or Formula.

Did Pontiac use the COZ code as well? Bill

Yup.. COZ was 3.73 posi on Pontiacs also.

If he knows what he's got, he'll be asking 10x what he paid for it, but hopefully you can get it...Good luck!

The COZ 3.73 12-Bolt was fitted to all '70 Trans Ams with the M21 4-speed, or M20 and M40 cars with the Performance Axle option.

Also available on '70 Formulas. My RA III / M21 Formula has a COZ.

If he decides to advertise it, I'll let you all know. I won't be buying it.

Dave

Race track deal! Thought those days were long gone.

I see it is now listed on marketplace, so just letting you know in case someone is in need. Good luck.
Dave.