Not only was the front bumper stamped from thinner metal but so were the front bumper brackets. I measured a set on an original Hemi Dart and they were half thickness of production. But they carried the same stamped part number as production parts.
I noticed the same in that original primer/black Hemi dart that Frank Spittle owned that was in Mopar Action decades ago. When I saw it in Vegas it was owned by a real nice guy from Louisiana.