It's got the fat front fenders of the F-500/600, as well as the Fender lights that the Medium Duty F-series got. The Fenders are "Fatter" to allow for the larger tires the F-500/up got.
So I would say it's a F-500 by the picture. But not a automatic...
Here is another picture of a 1965 F-500 with "Fat" fenders.
Then a picture of a 66 F-350 Dually. Notice the fenders are not "Fat".
Truck: 1981 F-150 Explorer / Engine: 300-6 California MCU Feedback System / Trans: T-18 - 4 speed / 2.75 Ford Rear Axle Open Diff.