We had a '95 F-350 7.3L diesel, auto, 4.10 gears, 2wd, crew cab dually. Bought new and put about 250k on it before the trans started to slip. We had a Banks Get-Kit (chip and turbo down pipe) to boost the torque from 425 to ~500ft-lb.
14-16mpg was the norm running empty. Don't remember loaded... We grossed 14-18k combined for a majority of its life pulling a horse trailer. OD on the flats and 3rd on the big hills.
Was a comfortable ride, easy to work on. Only downside was glowplugs, damn that truck ate glowplugs; was about as fun getting that thing started in the real cold as stubbing your toe. Plugging in the block heater was a must, but then only about half of the glow plugs worked on ours at any given time.
I actually looked at a couple of 7.3Ls before we bought the Dodge (my trailer isn't that big, lower purchase cost, the wife wanted a 3rd Gen Dodge). The crew cab Ford from that era has more interior room than my Dodge!
Had a '90 F-350 460/auto/4.10/4wd, reg cab single wheel on 35x12.50 tires. 10-12mpg empty. Bought used from original owner that carried a 9.5? cab-over. Was a good truck, just drank fuel. Luckily I drove this back when it was rare to spend more than $50 to fill the ~18+19gal tanks. Had to lock it in 3rd for the same trailer as the diesel, and it saw 2nd on the hills. The 35" tires did hinder it, we did put stock sized on it just to see the difference it made, still had no chance at running with the 7.3L.