Both of our 2004 (lb7) trucks are down with injector issues. 1 Had a kind of a knock to it but was not missing. Was low on power. Driver never runs it hard, just kind of piddles along. 52.000 miles. Always had a slight knock but it had gotten a lot worse here lately. Just 1 injector replaced. It's is now leaking diesel fuel badly were they had the line off.
Other was very hard to start. Still good power, no fuel in oil. Just very hard to start. 55.000 miles. Waiting on injectors now to get all 8 replaced.

My 2002 is still just a purring along. (knock on wood) Almost 95.000 miles.

Why those 2 and not our other 2? Mine is a 2002 and we also have a 2003. It only has about 45.000 miles.