These 3/8" screw-in rocker studs are used on all late model LT1, LT4, and any head not using a pushrod guideplate. This kit includes 16 of P/N 12552126 studs and use this P/N 12552126 for single service. Technical Notes: The lower thread section of this screw (that screws into the cyllinder head) is 7/16".
