[silverbullet07]

How is the pontiac rear end date decoded. I tried searching on line but what I found has not matched the 68 firebird ZM rear end. The three numbers next to the axle code and the three numbers above the pumpkin casting look to be Julian day numbers. How does one decipher the year on the axle.

He is a couple pictures of one I have showing the numbers.






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[crab]

Not sure on date, but year is 68 posi rear for firebird.
http://firstgenfirebird.org/1968-inf...68_id_numbers/

[silverbullet07]

Yes I know what it is. I'm trying to learn how the dates are coded.
The number next to the ZM is 262. I assume this is the Julian day of close to middle of sept. How do I know the year?

67-68 had ZM axles. Of course the spring perch was for mono spring in 67 and 69 had a 4.11 instead of 3.36.

Just wondering where a year code may be and if I'm right on the other numbers.

[crab]

Originally Posted by silverbullet07

Yes I know what it is. I'm trying to learn how the dates are coded.
The number next to the ZM is 262. I assume this is the Julian day of close to middle of sept. How do I know the year?

67-68 had ZM axles. Of course the spring perch was for mono spring in 67 and 69 had a 4.11 instead of 3.36.

Just wondering where a year code may be and if I'm right on the other numbers.

gotcha, lmk if you want any numbers off the one I have here, I just started working on it. Both my 67 rears have factory traction bars and the loops above the third member housing, the 68 does not have either.

[silverbullet07]

The information about axle codes on Wallace racing looks nothing like the codes on my two zm axles and information like this is what I always find.

http://www.wallaceracing.com/axledata2.htm

[Held for Ransom]

http://www.forums.maxperformanceinc....d.php?t=684407

When the Julian date code is used, you have to figure out the casting number for year ID. Your center section was cast on July 10th, 1967 and assembled on Sept. 19th, 1967. You car was probably assembled in early Oct. '67.

[silverbullet07]

Awesome thinks. I always wondered about that and never ran across it before. Thanks.