GMC Rear End Codes?

[TsgtE662]

Does anyone know the rear end codes for GMCs?

I found all of mine.

Option Code is: 4G80AC Rear PosiTraction A
Pass. side rear: 67890 and 126 4 5
on top, stamped is TPP0213 W an E slanted above the "3" area
front side is NF 3896839

on Driver side is: A 29 0 I assume means Jan 29 1970
and GM 51

I have searched every where I can think of and can't find anything else on it. The Diff cover has 12 bolts if that matters.
I have been able to decode everything so far as best I can except the rear end.

Thanks for any info/help.