For use on 3-valve 5.4L and 6.8L engines built before 10/9/07 and 3-valve 4.6L engines built before 11/30/07 found in many 2004-2008 Ford, Lincoln and Mercury The spark plug tends to break off in the cylinder head during maintenance. If this problem is not repaired properly, it can result in damaged or unusable spark plug threads and in extreme cases the possibility of a spark plug blow out. Repairs damaged threads or blowouts in 30 minutes or less per cylinder Insert dimensions: M16x1.5 I.D. x 3/4"x16 O.D.