I'm a bit of a role playing game geek who loves "The Morrow Project" and "Twilight: 2000." Being in a game of the former and running one on my own, I sort of fell in love with the Cadillac Gage V-150 armored car series as well as the Ranger series.
Actually, it is a V-100 but I use it as a pic prop in my games for the V-150. The V-100/150 series as well as the Ranger series were used in the Vietnam War and beyond, maybe this could fit the bill. Beyond that, the other quick solution is maybe ship Brink's armored trucks over.