This bolt is for any big block Chevrolet engine. The kit includes 16 bolts: 3/8" - 16 x 1.5". With wide under head flange with a 7/16 hex head, they are rated at 170,000 psi and will give a consistent torque load. Includes 16 hardened flat washers. Technical Note: Four of these washers are smaller in diameter and are used around the front water passages.