This is an injection-plastic military vehicle model kit.
From the manufacturer:
The m65 Atomic Cannon, often called Atomic Annie, was a towed artillery piece build by the United States and capable of firing a nuclear device. It was developed in the early 1950s, at the beginning of the Cold War, and fielded by 1953 in Europe and Korea. The cannon was transported by two specially designed tractors, both capable of independent steering in the manner of some extra-long fire engines. Each of the tractors was rated at 375 hp, and the somewhat awkward combination could achieve speeds of 35 miles an hour and negotiate right-angle turns on 28 ft wide, paved or packed roads.