Is this for real? '70 12 bolt

badazz81z28

Veteran Member
May 4, 2001
22,318
Alabama
I’m an amateur restorer but it’s unlikely someone will pull the axle cover to verify eaton posi date codes and GM gear sets

agree, same could be said about the casting numbers on the housing as well. It would have to be a meticulous build to have that standard. If the housing dates are that important, so will the guts. Look at Ron’s build, he is looking for date coded ball joints and rotors.
 

Gary S

Administrator
Lifetime Gold Member
Apr 14, 1999
24,656
Bismarck, North Dakota
Yep, you are correct!
I suppose I could check the # on it...
I've owned the car since 1980 or so and knew the second owner ....

Check the code on it. If it is a 3.73, it would be from a Z28. If it is a 4.10, it could be from a Z28 or a L78. If it is a 3.55, it is from a L78. If it is a 3.31, it is from a SS396/L34 or from a SS350. If it is a 3.07, it is from a SS350.
But, this axle was also used by Pontiac on the Trans Am and the Formula so it could be from one of them instead of a Camaro.
 

hwprouty

Member
Jun 14, 2005
42
Granite Falls, Washington
Check the code on it. If it is a 3.73, it would be from a Z28. If it is a 4.10, it could be from a Z28 or a L78. If it is a 3.55, it is from a L78. If it is a 3.31, it is from a SS396/L34 or from a SS350. If it is a 3.07, it is from a SS350.
But, this axle was also used by Pontiac on the Trans Am and the Formula so it could be from one of them instead of a Camaro.
I'll check it out, it had 3.73's as I recall.
With the 4 speed it didn't feel like 3.31!
 

Rosster

Veteran Member
Gold Member
Mar 1, 2020
1,038
For camaros, 3.73 will have COZ stamped on it, 4:10s are COO. Not sure whether pontiacs used the same codes or not (unlikely)
 




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