I have a 3rd generation camaro, look at the random ranting thread, there the same car with a different name, 3rd gen on the camaro at least ran from 82-92. from all the 3rd gen that i have seen from shows and on the street I have never seen a spoiler that big on a 3rd gen, i have only seen that big of a spoiler on a few 4th gen cars.
edit: on second thought i have seen a spoiler tht big on a 3rd gen, it was at a local car show about a few years ago. a guy had just dropped a 405 small block into it and added a few other tweaks....