My neighbor, a mechanic, had an earlier (7. 3) Powerstroke that was bombed, like all his trucks, & finally sold it after installing the eighth transmission.
Bought an '04 Powerstroke & burned up the engine pulling a toyhauler. He hadn't even put the license plates on, yet. Ford denied warranty, after tearing the engine down because he had a box installed & hadn't removed it for the warranty trip to the dealer. He had to tow it home with the engine parts in the bed of the truck. He rebuilt the engine, on his dime, & it ran well but, he was worried that it might self-destruct, again, so he sold it.
He then bought an '05 Powerstroke, with everything on it, & promptly blew that one up, also. This time, the dealer installed a brand new engine, for him.
Admittedly, he does run the "crap" out of his trucks & has the highest performing boxes on them, that he can find. I told him to turn the boxes down while towing & his answer was that "They are supposed to be able to that".
I wonder when he's going to figure it out?
Joe F. (Buffalo)