1977F-250 fuel capacity

Can anyone tell me the factory spec fuel capacity of the main and auxiliary fuel tanks on a 1977 F-250 custom pick-up?

Side mount tank shows both 22.5 and 20.5 gal as a replacement part at rock auto.
Rear mount tank is 19.0 gal.

That matches with my memory, too. I never ran my truck out of gas so the 2 gal difference was not relevant to me at the time.