1970 Camaro rearend

[DAVE H]

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

[luzl78]

z and ss

[dustinm]

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

[BCreekDave]

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.

[FTC]

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.

[big gear head]

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.

[L16pilot]

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!

[DAVE H]

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

[soundjunky]

$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. ;)

[luzl78]

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.

ss l78 and 350 got the 12 bolt

[Big Block Bill]

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

[L16pilot]

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.

[iluv69s]

70 Z , T/A or Formula.

[Big Block Bill]

70 Z , T/A or Formula.

Did Pontiac use the COZ code as well? Bill

[iluv69s]

Did Pontiac use the COZ code as well? Bill

Yup.. COZ was 3.73 posi on Pontiacs also.

[Budz]

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

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!

[keith k]

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.

[DAVE H]

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

Dave

[GM Powertrain]

Race track deal! Thought those days were long gone.

[DAVE H]

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