I used Eastwood's 2K chassis black spray bomb to paint my power steering box after it was rebuilt. It was convenient for me. Only time will tell how durable it its.
Originally I was going to powder coat the K and diff Kevin but decided that's probably over kill, this car will live a pretty charmed life when done and there are other areas the money could be better spent. I suspect this will hold up pretty well, a hell of a lot more protection then the factory ever put on them!