On Monday, February 13, 2017 at 7:44:06 PM UTC-7, wrote:
No markings. Were these manufactured with some standard rear axel or a variety of parts? Most look like a GM 48 inches wide, between brake drums.

Plenty of websites. The design engines were 283 and 327 IIRC from plans, so a '60's generation diff would seem to make sense. Several web sites with ID methods.

http://www.roadkillcustoms.com/hot-r...#axzz4Yd41BzKS

http://www.crankshaftcoalition.com/w...identification

http://www.jalopyjournal.com/forum/t...ential.975907/

What model and serial number Gehrlein?