In the cab 18 gallon fuel tank! That brings back memories!
I had a rare 1975 F-350 supercab! Trailer life did a test report on a white one, and I test drove that truck before buying mine in 1987. I got mine in red and white. Had a 460" V8 and C6 transmission. I had a 3.73:1 rear axle, something that was a excellent ratio, considering it did not have overdrive. Plenty of power, and still low enough RPM at 65 to get 10 MPG.
I also had a camper on the truck most of the years that I had it. It was also able to tow about 10,000 pounds. Without being over it's 9,600 pound GVWR. I had 9.5R16.5 tires on the back rated at 3,450 pounds. Front tires where a little smaller, and lighter duty.
The 'better' camper truck was the F-350 Super Camper Special, with the 7" longer wheelbase, spare tire under a cover on the passenger side, just behind the passenger door. It also featured a 40 gallon aft of rear axle fuel tank.
In 1974 Ford dropped the in the cab fuel tanks. Something about if the truck got on it's side (in a accident) the gas cap would fall off or rotate loose, and all the gas would spill out, then catch fire. GM had the same problems, and after 1975 all gas caps needed to be in recessed area, with a door over it.
I had great power steering! Extremely light, I could palm the steering wheel, and make three turns in a couple of seconds! That brings back some fun memories!
So is your dad's F-250 above or below 8,600 GVWR?
Have fun camping!
Fred.