So, I just went to Home Depot. I got some Rustoleum High Performance Enamel Primer and Flat Black cans. I hope a 15 oz can of each should be fine. But I'm still having trouble getting the clumps of 40 year old grease and dirt off. I've been taking some engine degreaser, letting it sit for 5 mins, then taking a steel brush by hand and scraping as much as I can off.

I may ask my friend to help me clean it when I take the housing over there on this weekend. I believe he has a proper cleaning station I could probably use. On that note, yes, the diff is going to be built soon.