OK,
Here's what I know:
71 or 72 Panel
5-Lug
2WD
Here are the pics....
View from back cover
View of Pinion Side
I want to guess "12-Bolt", but I don't know enough about this type of vehicle to be 100%. I have seen the Eaton rears before and they are a lot "rounder" and the cover is almost a perfect half-dome shape, which this one clearly isn't.
Anyone? Lots of good emoticons for whomever knows....