I'd look somewhere else, anywhere else. 

I have a 2003 F350 6.0 with just over 210k miles on it. Runs great (at the moment) but has been in & out of the shop since it came to the farm with 170k. Best thing I can say about the truck is that it has made me a better mechanic as I've been doing all the work myself recently.

If your son is interested in becoming a diesel mechanic it might be a good fit!