I use to notice as a little kid the early Firebird had the single round headlights and the "400" emblem. Then they upgraded him to the quad headlight and no more 400. He had the Esprit or however you spell it.
I read something that said all the cars used were Formula 400s because the standard models wouldn't necessarily perform and hold up to what they were put through. They made the cars look like Esprit models to seem more realistic for his character. Garner didn't like the look of the 79-80 models so they continued to use old ones.
A friend here in town owns 2 of the original cars. He's a Mopar guy too.
Yes, they removed the scooped hoods to make them look for mundane and everyday.
He also owns an original Cookie Jar and lots of other show memorabilia.
...helping stuff a Hemi into an A-body:
