IIRC, Ford's relationship with Navistar ultimately fell apart because of the 6.0 PSD. I won't forget the 6.0 F250 I saw on the grade coming north out of Castaic on Labor Day weekend several years ago. It was lifted a bit, dragging a toy hauler around 28', and blocking both truck lanes by Templin Hwy. Traffic was crawling, so I got a real good look at all the oil and chunks of iron strewn under the truck leading up to the engine. It may have been overloaded, overheated, over fueled, etc, but it was still a 6.0. Within months of that I was following one home that was billowing blue oil smoke...I got a video of that one.
I like Fords, but think I would prefer a Dodge/Cummins as diesels go. Mmmmmmm......6CT swap.