Here is a very nice shot of two Marmon Herrington Mark II
armoured cars in Syria, 1941. Note in each car the pair of headlamps tucked into the bottom of the compartment behind the frontal armored doors.
Whereas headlamp location is a good distinguishing feature between the Marks II and III, methinks more obvious yet is the placement of the spare tire. And that location reveals there were variants within the Mark III
armoured car. In the first two images, the location of the spare tire high on the left side is consistent with the presence of the single rear door into the car. When no such rear door was present, the spare tire was mounted on the rear of the car, as seen in the second pair of photos.
Now the questions remain, which variant of the Mark III
preceded the other? And did the later one entirely supplant the earlier, or did they coexist as manufactured
vehicles, at least for a period?