Recent post made reference to Brass Tag Cars, something new for me.
Saw this picture of a tag on this link:
https://www.autoevolution.com/news/original-owner-one-of-one-1968-mustang-428-cobra-jet-sports-huge-three-speed-surprise-234507.html#agal_21 (https://www.autoevolution.com/news/original-owner-one-of-one-1968-mustang-428-cobra-jet-sports-huge-three-speed-surprise-234507.html#agal_21)
I'm not that surprised if this car has that brass tag on there. I do see the picture.
There are several early Boss9's that have been found with brass tags.