I have seen these types of trucks referred to as "Box Trucks" in a couple different places. Although the name certainly makes sense, I don't recall them be referred to as such, back when I drove one. Back then they where referred to simply as "Straight Trucks"! Times change and like everything else the names in prominent use at one time fall out of favor as quickly as they fall into favor. I drove a "66" Ford cab-over straight truck with a box on it in 1968-1969. Then, I was a truck and track mechanic in the U.S. ARMY from 1970 to 1972, although after 16 weeks of mechanics school; 8 of truck and 8 of track, I never touched another track, when I got to my Permanent Duty Station. I was very happy with this as everything on a track required heavy lifting! In the U.S. ARMY we called our straight trucks Duce and a Halfs and 5 tons!