I found a set of C3 Corvette Aluminum wheels and decided to try them on my Grand Prix. The only issue is the lug nut thread pitch for the C3 wheels is 7/16 and I need the 12mm x 1.5 thread pitch lugs nuts. The C3 uses a special type lug nut with a flat washer and not the standard acorn style that we use on our G-Body's. Has anyone encountered this problem and can you suggest a place where I can purchase them? Thanks in advance for any leads.