Go-wing differences......

Can you tell if yours is fiberglass?? What do the brackets under the trunk lid look like?? I also know that the original wing were heavy!! My 71 Demon was a factory rear wing car. I can remember when I had the car painted in the early 90's the bodyshop took the wing off and I took it home for safe keeping. Well I went to pick it up, and it was not near as light as I was expecting.