ARP Main Stud Kits | Multiple Chevrolet Fitments (135-5801)Main Stud Kit by ARP ARP main stud kits help eliminate main cap walk fretting and protect the threads in your engine block. They include studs made from 8740 chromoly steel and heat treated in house to 190,000 psi tensile strength rating. The precision J form threads are rolled after heat treat for much stronger threads than the competition. Kits come complete with hardened parallel ground washers and high quality nuts. Add confidence in the strength