I have a '99 F350 Dually with the 7.3 Powerstroke.

100,000 miles on it now.

It makes me a living pulling grading equipment around.

Transmission overdrive went out around 84,000 miles, so I replaced the
transmission, and installed a better torque converter at the same time.

No other problems. I'd buy another one just like it.

14mpg around town unloaded, 18-20mpg on the highway unloaded, depending on
my right foot.

Spdloader

I have an 05 F350 Lariat 4x2 Dualie with tow command and all the options.
I happy with it with minor exceptions. It pulls my 12,500 lb fifth wheel
with ease. The tow/haul feature is great, just don't use it descending
on steep wet roads with no load.
The tow command or built in brake control works much better than the 01
Dualie with a Prodigy controoler, I had.
The rig averaged 10.4 mpg on a recent 1200 mile round trip, mostly
Interstate with two mountain pulls.
I don't care for the initial dead pedal from takeoff that is mapped into
the drive by wire throttle.
I don't like the flat seated, hard as rock, Captains chairs or the split
bench that was in my 02 either. On a long trip my rear hurts.
We had an 01 Dodge Cummins that had great seating for a long trip. My
seat never got sore.
In the best of worlds I would like to have the Ford Superduty Truck with
the Dodge Cummins engine and the Chevy Allison transmission.
I like the Dodge Cummins engine but the truck it is wrapped in is junk
and the transmission is not up to the task of the diesel for the long haul.
The Cummins in the Dodge doesn't have a Cat or EGR and Cooler and two
less cylinders to be concerned about.
All the ratings of the Big Three are rigged. The Dodge Cummins rating of
600 lb ft of torque is with the air conditioner on and the engine fan
operating. The computer cuts back the output without these operating.
I have driven all three empty of course. The Duramax is perhaps a tad
stronger, especially off line but in all the towing test by the
magazines the Ford outdistanced the other two by big margins.
The Dodge is the cheapest to purchase, the Duramax the highest that was
before all the hyped so called employee pricing.
The Ford has the best quality and features of the three except I would
like to see the reccomended oil change interval based on engine use of
the Chevy computer display in the Ford.
This is just my .02 and I certainly don't have the corner on the subject.