Hey NITROUSN, You may have just hit the nail on the head. I went and found the invoice from Summit Racing that came with the Cragar Mags. Here's the part number on the invoice: CRR-61C4654 14X6 5on4 S/S Cragar. It looks like they are the 61C type mags after all. So this type of Cargar S/S wheel takes & uses a tapered seat lug nut. Stupid Me, I've been trying to use the old school style Cragar lug nuts with the shank ends. No wonder they kept coming loose on me. Thank you everyone for all the input. Looks like problem solved.