DoctorDiff not taking calls or emails?

I got him via e-mail multiple times with no issues. At the time, he had no 8-3/4 Power Lock diffs available because he had trouble getting spider gears from his vendor. Supply issues are a problem with just about everything these days. I ended up buying one of his Sure Trac II units. It's not installed yet because I also got some Mark Williams bearing caps that need milling.
Should be pretty stout after that... I hope.