My truck is a 99 F550, Pickup bed. 7.3 with 4.88 gears with 218K on the clock. Paid $7K 4 years ago. It was a ranch truck here in Az. Worked towing Horses and bucking cattle. Then I put an 11 foot cab over on it and pulled my Rhino on a utility trailer. Now it tows my 40 Ft toy hauler. weighs 15K dry and close to 20K when completely loaded.
Now has 268K on it. Outside of standard maintaince had to replace an alternator and exhaust manifold gaskets.
Empty under 70 MPH flat Freeway 15 MPG. Cabover and utility trailer Hiway driving some 6% grades 12 MPG. 20K 40 ft toy hauler loaded flat 10 MPG. Throw in the 6 to 7% grades getting to the mountians from Phoenix 8MPG.
It has been a great truck.