My 73 Challenger's box showed no signs of paint. It was just greasy and rusty. I wire wheeled it years ago and sprayed it with cast blast paint. It started rusting through the paint so my plan was to get it down to bare metal and RPM it.

While stripping off the cast blast, I saw a lot of soft black paint on the plastic scraper. Sure enough, there was black paint under the surface rust.

I think if more people soaked these boxes in EvapoRust, they would see the black. The rust really grows around the paint and no black can be seen.