5.4L V8

2003 was the last year Ford used the DG508 style ignition coils with the angled boots for the 5.4L V8 engine. The next year engine Ford used a different style ignition coil. These parts for the 2003 F150 wear in the same environment, and it is common practice to replace all at the same time if one fails, and the ignition coils are several years old.