Unique design helps prevent breakage by locking the plug porcelain core to the plug hex allowing it to turn as one complete unit. Will also pull plug porcelain core if plug hex only is removed. Detailed Instructions to maximize success rate. Works on: Ford 4.6L 3V V8 engines used in 20052008 Mustang, 20062008 Explorer. Ford 5.4L 3V V8 engines used in 20042008 F-Series, 20052008 Expedition, 20052008 Lincoln Navigator. Ford 6.8L 3V V10 engines used in 20052008 F-Series 250-350-450.