There's some pics here https://www.camaros.net/forums/133-bu...stored-79.html of Chick's DF code wheels. Maybe he will pick up on this or send him a PM. From the depth of the valve stem slot, I'm thinking yours are the same. Out of curiosity, what's the backspace on your 5" wheels and do they have a code ?
DF (15x6) are 4 1/16" BS.