Injectors.........

[BRIM]

How does one know when its time to replace ??

[rameye]

Usually replaced when you experience declining performamce/power, harder starting, declining fuel mileage.

You would have driven the truck tens of thousands of miles in order to gage this. They decline very slowly, possibly performing reasonably between 80-150K or beyond.

Hope this helps.

[Kennedy]

The 6.2 6.5 has a usefull (prime) life of 80-100k. They will run perfectly fine beyiond that, but are not in their prime any more.