Yes, on the 1-ton Advance Design (which is what we are talking about), duallies were an option. Look in our Gallery and you'll find lots/many/some of them.
The open hood presents a nice clue -- the shorter shroud covering the top of the radiator and mounting the hood latch. On the 1-tons and smaller, the upper shroud is taller and more pronounced. On the Big Bolts, because of the taller tires needing bigger fenders which in turn require a bigger grille ... smaller shroud needed.
Like Grigg says, if we had more resolution to that photo so we could make out the detail of the front wheel hub, we could see if it is a bolted-on round cap (2-ton) or a screwed on hexagonal (?) cap (1.5-ton).
