From CRG...
Spoilers (D80): The spoiler option was not available in 1967 on any Camaro. It became available as an option on all cars (except those with a rear antenna) in 68-69. It was not mandatory on any car, except for the 69 pace car replicas and later 69 Z's. The narrower 68 spoiler was used on the 69 Camaro up to January - March of 69, when the wider 69 spoiler was phased in. One of the torsion bars on an original spoiler equipped car will be of larger diameter to compensate for the weight of the spoiler. The front center of the 69 subframe will have a drilled hole to mount the center brace of the front spoiler.
Paul