Mystery panel/service/jail transport/milk/mail???

This is on a friends farm, they thought it was a milk truck, I’ve not seen anything like it. Lots of rivets and only a single side door into the back which is partitioned off from the front. Any ideas??? My best guess is Chevy or Dodge for make and possibly military off the color. Thanks HAMB detectives!

 

Maybe some value transport or prisoners?

 

It's one of 'em:
https://bringatrailer.com/2017/12/07/signal-corps-radio-truck-1941-gmc-k-18-project/

 

1941 GMC military radio command car

 

Looks like it would make a bitchin' 4wd camper rig if there was more of it still around.

 

All it needs is a front clip of some sort and a drive line .

 

Some of the military. WW2 panel's were a mobile machine shop too. In the second photo of the rear, you can see the WW2 cats eye tail light, and its proper mate, the glass marble reflector

 

that high body style was also used as FDC fire direction centers for directing artillery fire sent from forward observers . radio- phone, etc