Sorry, I meant to add this Ford direct information
This article supersedes TSB 08-1-9 to update Vehicle Applications, Service Procedure and Part List.
Some 2004-2008 F-150, 2006-2008 Mark LT, 2005-2008 F-Super Duty, Expedition, and Navigator, with 5.4L 3-V engine; 2005-2008 Mustang, 2006-2008 Explorer, Mountaineer, and 2007-2008 Explorer Sport Trac with 4.6L 3-V engine; 2005-2008 F-Super Duty, 2006-2008 and F-Stripped Chassis, with 6.8L 3-V engine may experience difficulty with spark plug
removal. This may cause damage to the spark plug and leave part of the spark plug in the cylinder head. Affected engine build dates are as follows: 5.4L 3-V and 6.8L 3-V before 10/9/07, 4.6L 3-V before 11/30/07. ACTION
Refer to the following Service Procedure for techniques to remove the spark plugs
and extract broken spark plugs.
The engine build date can be read on the left hand cam cover information sticker.
To remove spark plugs without damage, it is necessary to adhere exactly to this procedure before removal is attempted.