The smaller one was stock 5/16 base rocker stud. The rocker stud base on #1 exhaust was stripped out and rocking back and forth. A few others were coming undone too. The bases are torqued to 25lbs but are no match for power or engine or the springs or lift of cam or something? The larger one goes deeper into head and is thicker 7/16 base. Going on Aluminum heads.