New ARP oil pump stud kit. This is a chromoly stud with 6-pt nut.  For aftermarket high volume style aluminum pumps (cast).   3.125" Stud.  Fits:

67-97 Corvette, all small block models/LT1 w/ aftermarket high volume aluminum pumps
67-97 Camaro/Firebird, all small block Chevrolet models/LT1 w/ aftermarket high volume aluminum pumps