I'd be interested in any reports of towing with the 6.4 at higher altitudes, say 6000 to 9000 ft.
Also, re mpg reports on this thread or other threads, it would be helpful to everyone if mileage figures were accompanied by how calculated -- hand-calculated or digital read-out in the TV. Personally, I'm only interested in hand-calculated figures and pay no attention to vehicle computer generated numbers, and I also ignore the numbers if method of calculation is not disclosed.