I know this topic has been covered a lot over the years in the auto world but I haven't found much info regarding longevity if left unchanged. Anyone have this engine and never do any work on the cam phaser? Did you eventually experience issues aside from the knocking? Eventual serious engine problems? My '04 runs great but that knocking is scary and annoying. It's not nearly as bad as some I have heard and I bought it used so I don't know if the cam phaser has been worked on. I have heard a lot of mixed talk about whether or not it is worth changing them. Any thoughts from you Ford truck guys here?