I don't know if it is still available on news stands, but in the October 2011 issue of Diesel Power Mag, there is an article titled "Stop Your 6.0L From Failing". they useed Bullet Proof Diesels air-to-oil cooler kit and egr cooler kit.
Don't take this the wrong way but if you don't want a vehicle to have issues right after you buy it then buy new, but even then there are no gaurantees. i feel that a lot of people buy a diesel thinking, "these engines can last forever so that means i can beat the living **** out of it and not worry about any maintinence and nothing will happen". i have yet to see an engine that you can beat the living **** out of and have it be reliable for a long time. the point is people don't take care of these things and then get pissed when they don't work. in another diesel mag that i have there is a picture of a 6.7L cummins and it said that it was found in a junk yard with only 50K miles on it. geuss what, it had 50K miles on the oil. like anything you take care of it and it will last as long as it physically can.
this is not directed towards the OP or anybody else. it is just how i feel.
Now, back to troubleshooting.