I have a set off of my 88 IROCZ that are polished aluminum, I think they also have a clearcoat. Anyway, each pulley has a hand engraved number on the back side. The crank is 4011, the water pump is 4012, and the alternator is 108. These are nice pieces, other than some idiot gouging timing marks all around the crank pulley interior. Any ideas? Did some searches for Camaro/Firebird and those numbers but got nothing.