Hello.........

I have a '68 SS396 (built the 4th week of December) that is numbers matching with the exception of the differential. The Protect-O-Plate states that it should have a stamped number of BM1212G, but the actual number on the differential is BU1105G (3.73 posi). However, when I look at the 'decoders', the BM differential was not available on the '68's and came into production for the '69's.

Can anyone shed some light? I can understand that the differential may have been changed, but how could the Protect-O-Plate have a code that did not exist in '68?

Thanks!

BM = 3:31 non posi rear for 1968 same as in 1969, this code was used both years. Looks like the rear was changed out at some time in the past.

Thanks Jonesy,

Anybody have any ideas as to where I could start looking for the correct BM1212G differential?

Not to discourage your search, but the chances of finding that code with your EXACT POP date are not that great unless you can track down where your original diff went.
Check the casting date on your existing diff, if it is 68 it predates your car OK.
If you wanted to you can have the tube restamped with your code.
The stamps are not any thing that special on the diff tube, and the codes are often crooked, although the date is usually fairly straight.
A lot of people frown on restamping, but you are not trying to clone or forge a car, just put it back to your protecto plate numbers for your own peace of mind.
You could also put a ad in the TC classified wanted section, or simply leave it with a blank tube.
Good luck with your search.
Just my .25 worth.