I sent the pictures to my nephew who worked at Whiteman before he transferred to the Space Force. He said they used these vehicles to do maintenance (radio, electronics etc.) mainly on the flightline (as evidence by the FOD (Foreign Object Debris) disposal bucket inside). Stuff was picked up from the runway and put in the bucket. He said he spent many a night sleeping in the back, waiting for something to break.
Just thought I would pass that along. 50+ years ago, we drove Step vans for electronic maintenance when I was in the AF. Good luck if you go that route.