ARP 134-3609 Pro Series Head Bolt Kit (12 Point hex) Chevrolet All Models -03 MPORTANT NOTE: MUST HAVE 2 different length primary head bolts plus a third smaller bolt. There is a Mid-Year split on the head bolts, If you have ALL SAME Size head bolts this kit is NOT for YOU, see part 134-3610. DO NOT BUY THIS KIT until you have pulled the head and verified the size.