The Unimog is a Mercedes AWD military vehicle platform that many militaries use, in many configurations. A local brewpub has a firetruck version, that they have converted to a Biermog, so they can bring kegs of their beer to your event. I highly recommend both the food, beer, and converted military vehicle, at the 5 Seasons Brewpub.
As has been noted on other treadhead threads, I believe by archy, the South Africans, as you mention, as well as the Rhodesians, developed a number of mine-resistant patrol vehicles that have the characteristing V-shaped lower hull. Some were probably Unimog-based.