I was a kid at the Daytona 400 race when it first appeared. It was never factory installed for the first race. It was installed at the track, Nascar didn't like it and went to the local Dodge dealer and found out there was a factory part number that was referenced to the spoiler on the Charger pre race, that won. My memory of that spoiler is from seeing the car in the pits, and that it was a big controversy, it was such an oddity at the time for a stock car, it was just a flat piece, and stuck up less then 1/2"?. However I have seen pics since and seems it was higher then that, so I don't know it those pics were from other later races, because it seems more spoiler is always better then less. I don't remember the detail of being one or three pieces, I thought it was just one. I might have some pics from the race I'll look for.

Edit I couldn't find any personal pics that were pertinent, sorry