Just read over two hours of diesel forum posts re: the '06 Ford (Navistar) 6.0L diesel and you have to dig deeply to find anything good. I'm a marine diesel guy and not familiar with some of the emission language but there are repeated mentions of turbo problems because of exhaust reburn soot in the turbo blades, the EGS (whatever that is), head gaskets blown from overpressure turbo.
The best I can glean from it is that the 6.0 was a decent diesel engine until Ford had to make the necessary modifications to meet emission standards. After that specific problems seem to plague that engine, which can prove very costly after the 100K warranty expires.
I don't have the $$ to do repairs 4k from now so I'd best pass on this one.
I didn't realize that you can't find a long box bed with a 4-door cab, which I need for a 145 lb (and growing) pet. I'll look for a tapered front 5W or a slider if necessary.
Thanks very much for your insights.