They came on some '67 Hemi Chargers only, but not all of them. I have never seen any numbers on how many but my guess is a 1/3 of the '67 Hemis had them. If there is one on a '66 it was added as they were also available over the counter.

The originals were aluminum. There was a fiberglass copy made around 25-30 years ago but the way it mounted and the two end pieces were different. A correct repop was made about 5-8 years ago out of aluminum by some one in WA.

I owned a '67 Hemi Charger with a spoiler for 10 years. It was missing the broadcast sheet so I don't know for sure it came with the spoiler. AFAIK, the spoiler doesn't show on fender tags.