Actually, serial numbers don't always tell the tale on 99's. I would go here and ask these guys:
http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/forums/40/1/Savage_Collectors
They will know the answer. Incidentally, I have a 99 with a S/N of B089XXX and mine was made in the 70's...