Yes, it is.
Superior had a completely different roofline and styling for their military ambulances. The military units required an all-steel roof (while Superior was manufacturing their civilian ambulances with fiberglas roofs). They were distinguished by having the angle of the raised roof angling forward on the front, and rearward on the back - basically, opposite of the way you would think, not aerodynamic at all. I don't know if there was a specific reason for the "opposite angles".
They were also rather plain. Originally, it would have had just a single beacon on the roof, and no tunnel lights. It looks like this one was sold and became a civilian ambulance, and had a few more lights added to it. Also, no chrome crosses or other extraneous trim on the sides.
