What you see is a casting date. It is cast into the housing...not a separate "plate". Take a look at the two "screws"...you'll see they are different. This is how they differentiated between shifts. One shift would use two identical screws, the next shift would use one different screw. The actual plate would have been screwed into the mold itself.
HERE are some of my pics, and info on diff numbers, etc., to help ID what ratio, and date you have.
btw...best I can remember, that code you have is for June 23, '75. So, if your car was built after that date, it is correct for the car. That date, tho, is
only for the rear cover...not the rest of the diff. The main diff housing will also have a similar casting date on it...might be the same date, but prolly not. It would be fairly close, however.
|UPDATED|8/29/2013 7:35:05 PM (AZT)|/UPDATED|
______________
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"