"Air breather"
Not sure if your asking about
1- Oil breather cap - driver side valve cover? Its chrome plated
2- Air cleaner? - Painted engine color or very close to with a chrome lid or top
3- Thermactor (smog) air filter canister? Semi-gloss black as a unit along with the wing nut
4- PCV hose or valve? Depends on what part
Or another part
Did the picture thread of the unrestored S code GTA San Jose built fastback in the Unrestored Picture Thread not have a picture that helped? Looks like it was likely built within a few weeks of your car