C2 Unusual Rear End Date Stamp

[Daniel B.]

I am new to posting on the Forum. Thanks for all the great help and advice the forum offers. I discovered my '67 L71 apparently has an unusual rear end date stamp. The stamp reads AZ 7 C 10 (the casting shows K 4 6). The specs show the AZ decodes as a 1967 3:55 posi. No problem with this portion of the stamp. But according to the references, the date portion of the stamp should be all numeric and not contain any letters. Is the 7 C 10 an alternate stamp for March 10, 1967 on a replacement differential, or is there some other known explanation for this stamp? Or is it just a botched stamp by someone clueless? Photo is attached.

[Timothy B.]

Re: C2 Unusual Rear End Date Stamp

Daniel,

Welcome the NCRS forum.

I am thinking that rear is from a 1977 car. I believe that date format is typical of that Era and I think the AZ code was still used but not sure what ratio it denotes.

Do some research in the archives if you have time and you may find the answer.

[Paul D.]

Re: C2 Unusual Rear End Date Stamp

As per my trusty old GM Parts book, AZ was only used in 65, 66, 67, and 69 and only with Big Blocks. 3.55 ratio with posi H.D.. Chip.

[Edward J.]

Re: C2 Unusual Rear End Date Stamp

Dan the stamped numbers and letter are not typical, it appears to be a re-stamp,