Factory original leaf springs were not painted. They were identified by small stamped letters/numbers plus with painted colored stripes for easy reference on the assembly line, matching to the build sheet.
It sounds like NOS springs were painted so that they did not rust sitting around on a shelf. I don't know if they were typically stenciled or not.
I would not consider what Scott Drake is selling as NOS, I would consider them reproductions. There are a few suppliers out there. I ended up using Eaton myself, and I had Eaton break them down and shot peen them for me to remove the paint. If you look at other threads you will probably determine that none are excellent from the perspective of look. The Eaton springs are a bit too squared off at the ends. With some work you can make them look more like factory springs. Also read the threads on the spring clamps and determine how you want to proceed there.
From what I've seen over the years, NOS springs are pretty difficult to come by, particularly compared to other items.
