Stage 8 Locking Header Bolt Kit with 8 millimeter Bolts for Ford 4.6 and 5.4 Liter Modular Engine features locking header bolts for Ford 4.6 and 5.4 liter modular engine with 8 millimeter bolts up to 2004. It includes (16 ea) 8 millimeter - 1.25 X 25 millimeter 6 point bolts with a double hex head (includes 3/16 inch recessed allen head) and matching locking retainers and clips.