Bill,
One other thought occurs -- mechanic mentioned rear is of an older type not in production any more, making me think it's more likely to be the Eaton HO52 mentioned by another fella in this string. I'm kinda old-school and would love to keep the 8-lug standard of that vintage. I've tried to keep everything else stock, resisting urge to 'hot rod' it out.
Regards,
Jim