It's a neat looking combo. The date of the photo is questionable. With the M100 tub the photo dates no earlier than 1950. Looks like a small unit has produced a special purpose utility vehicle to fit their unit's needs on a local level. I doubt any high level of authority was involved in the project. The tub without a tailgate sacrifices the true utility of the M38 & CJV35, CJ2A & 3A/3B jeeps of the 50's which all had tailgates.
The frame looks stretched. If you view the bottom of the frame rail, I see a flat there on the side of the rail. Maybe angle iron? It actually looks pretty neat. I like pickups, so I'm a sucker. I don't think I'll cut up my MB or GPW though.