not exactly sure of RPMs but once a year 4 guys, 2 dogs, a 16 foot enclosed trailer full of greenhead gear decoys/blinds etc. make a non stop track to Canada. Its been at least 24 hours every trip we've made with no layover(once we drove 32 hours straight..... And normally only once or twice do we shut the truck off long enough to eat.
We drive about 85 to 90mph into a cold October north wind.
I believe that you should change the oil, keep a clean air filter ( I use K and N) on and "DRIVE IT LIKE YOU STOLE IT"
As far as I know, and I'm no mechanic, but 2200 is about the right range. We have several F 550 work trucks that push almost 3000 rpm at 75 mph and they hold up just fine. So you're in good shape.
The biggest worry we have with our trucks has to do with the injectors. We are constantly replacing injectors in those fords.
Yes, because the motors are the same in the F250, F350, etc.... Now I'm not sure how the changes made in the new motors (2008) will affect this problem.
Here's an example, and I'm doing this by memory, but the truck I drive, which is an '04, has 130,000 miles. It has had injectors replaced 5 times, with the first coming at approximately 60,000 miles. Luckily, Ford's engine warranty lasts up to 100,000 miles on their diesels, so it doesn't cost TOO much to replace them when they happen before then. But when they start failing after 100,000, then it gets expensive to replace them.