SLP Installation Kit, 1999-04 Head-and-Camshaft, 1st Design Early LS1 Block (long bolts) Make this kit a must when installing one of our SLP Cylinder Head and Camshaft packages on 1999-early 2004 1st design GM LS1 blocks with three different head bolt sizes. Kit comes complete with all necessary gaskets, seals, GM head bolts and hardware that are required for your assembly. NOTE: Includes all parts shown in photo.