Pretty sure that I heard the story here on Moparts many years ago. It originated from someone who had been at the assembly plant and seen a pallet sized box of multi-colored trunk latches being disposed of, and they asked what was going on. I think the story was relayed by someone who had interviewed this person. Maybe it was Dave Walden?

I was mainly focused on E bodies at the time.
I'm not sure what other cars it would apply to (if any), but my guess is that if that was the process, then it would have been used on other cars made at that assembly plant. (Hamtramck)

Tav