PRW 0345501 1.52 x 7/16" Aluminum Rocker Arm for Pontiac 287-455 and 4.3L V8 1958-81 Designed to meet the demands of most high-lift roller cam shaft profiles Specially machined to accommodate larger valve springs and retainers CNC machined pushrod cups and heat-treated Cr40 roller tips Internal oiling system for long lasting performance PRW RockerLocs included