They all had tank in cab, Ford stopped in I think 77ish. Fumes with today's gas would be my concern. Nice truck, have fun finding all the "Farmer Fixes", I swear its a old truck right of passage to have something poorly rigged.
I had two Ford pickups over the years. The '69 F250 I traded for had two tanks and two filler necks, one tank behind the seat and one under the bed.
The '77 F250 extra cab that replaced the '69 also had two tanks and two filler necks. Both tanks were under the bed and both fuel doors were on the driver side of the bed side, one toward the front and one toward the rear of the bed. That truck got me through the mid-70s fuel rationing since it had commercial plates and I didn't have to do the even/odd day gas fillups. I always kept the front tank full and only drove the truck on the rear tank. I used the front tank to siphon out of for either of the other cars we had at the time.