[motto]

Hi Lionel
The large single tyres on the bolted wheels I believe would certainly have been a military specification. This type of wheel is usually referred to as being a split rim. Blitz wheels were 16 or 20 inch but the Chevs used by the Australian Army as far as I know were 18 inch. If I recall correctly tyres were 10.50 - 18.
The 20 inch dual wheel setup was supplied concurrently. Trucks came with either wheel type as ordered.
Another variation is in the weight of the front axle. The line up of Chevs in the Alice Springs camp photo have the heavy axle which uses barrel roller type bearings. This is indicated by the domed bearing cover held on with six cap screws.
The vast majority of L/L Chevs came with the lighter front axle which used bicycle cup and cone ball type bearings. The bearing cap on these hubs was a pressed steel screw in cup that sat in a recess.
The trucks with the big singles seem to have used a different type hub again.
The big singles also required a different or modified front mudguard. There was quite a variation of widths and cutaways.
18 inch wheels are rare and 18 inch bar tread tyres almost impossible except for maybe 11.00 - 18 which were used on the Gamma Goat.
Lighting wise, the military contract trucks you would think all came with black out lighting but some appear to have the civilian type elongated parking light on top of the headlight which had a milky coloured lens. The tail light in your photo may well be original. The true L/L trucks 42 to 45 all seem to have BO lighting with the standardised main lighting switch and BO front marker lights as fitted to US military vehicles. Some even had the BO driving light. I assume they originally had the matching tail lights.
The foregoing is only based on what I've seen over the years and may not be completely accurate as variations keep popping up.

David