Rear Suspension Parts - Finish Questions

Well I think or should I say I know that the factory wasn't real consistent when it came to painting chassis parts. My 69 Swinger had painted U bolts and plates in a semi black and my differential housing was the same. My front control arms were natural. Now a friend of mine and we bought our cars within a couple of months of each other his had painted control arms and painted leaf springs and shock plates. I can't tell you why but I know that back in the day I think the factories kinda did things on different shifts from one another.

I know what my car had on it because I still have it and when I restored it a while back I can remember what was painted and what was not.