If I remember right, GM wheels have a 2.77 index in the center of them, the Moser drive plates are 3.06, so the wheel won't slide on to the hub, so the hub/drive plate must be turned down. I'm actually running 5/8" studs because my Mustang does so many track days. I originally ran metric on the front, and 1/2" on the rear. At VIR I had a one of the ARP studs break, the head just popped off while I was torquing the wheels. It kind of gave me the willies so I upgraded to the 5/8" studs, probably way overkill, but it makes me feel better.
