That is a International Harvester AACO Mk3, may be from the time of the Vietnam war or a bit later.

Btw., I have been driving around in on of these for quiet a bit around 1980.

A Bedford RL
It was stone old already then, at least 25 years. And it had a bit of a... comfort gap, lets say. But since it had a petrol engine, it was incredibly fast downhill, because the engine would rev higher and higher, unlike a diesel. Only coming to a stop was somewhat of a problem, when you are doing 130km/h in that. :)