What Style & Knurl for Disc Brake Wheel Studs?

I'm trying to order longer wheel studs for the front of a '72 Dart with BBP '73 Discs, but I'm having trouble finding out what size I need. They're 1/2"-20 studs stock length at the moment and I'm looking to get about 3/4" longer to work with the Bullit wheels. Can anyone tell me what size knurl these should be?
Thanks,
Jon
Author: admin