Fits 1955-1992 Chevrolet 262-400 Small Block & 1965-1990 396-454 Big Block. They are made from Grade 5 steel for strength and durability. The bolts are zinc plated to resist corrosion and provide a clean professional appearance. Sold as a set of six. Three 3/8-16 and three 3/8-24 mounting bolts with three lock washers.