The #76 is not a replica, and does not have a vinyl top.
One story I heard was that these cars had been acid dipped too much and that the roof failed during qualifying for one of the races. So in a mad scramble to fix it, they went out and rented a new Challenger, and cut the roof off to replace the one on the race car!!
I am not clear on the entire story of the #76 car and the #77 car, however I do recall that the 76 was an automatic! The #77 was a manual. However when I saw the #76 at the Nats it had a manual.
It was raced in SCCA events until the early 80's relatively unchanged from how it was in 1970 other than the paint, and some odds and ends. It was raced by a driver with spina bifada named Troy Waldren, the automatic facilitated this handicapped driver being able to race it. I'm not sure why it was made with an automatic back in the day.
There was a history of the Challenger and cuda Trans Am racing history in the "All American Racer" magazine put out by the late Special Interest Auto Club sometime in the mid 80's. In the article it said that the #77 car had gone on to race in Grand National events after its Trans Am days were over, and that it had been beat up and redone so often that no one would recognize it. Therefore I was surprised when I started seeing pictures of the restored #77 car racing at vintage events a few years back.
We talked with the owner of the #76 car some at the nats and what he told us didn't agree with what I had read in that article 20+ years ealier. He said the car had been raced for a number of years with different bodies, and that the chassis was eventually stashed away with the owner unaware what it actually was, other than it was unusually well constructed. After the chassis was tracked down and purchased, it was restored back to what you see today.
If anyone knows more of the stories behind the #77 and #76 cars as they exist today I hope they will share.
One memory I will take with me forever is back in the mid '80's, Troy Waldren decided to sell his car, complete with trailer and several spare engines, and the asking price was $15,000 IIRC. I was in college and thinking how this was a once in a lifetime opportunity. I had no where to keep it, I could have somehow scraped up $15K, but I certainly wouldn't have any money or time to restore it back to its 1970 look, so I never pursued it. Almost 25 years later I still probably wouldn't have the means to properly care for this car!
