During the war, the Americans need a mobile anti-aircraft gun. The popular M16 MGMC was the best solution for fast and cheap production. This was a M3 halftrack equiped with a Maxson M45 Quadmount AA-gun. Those are four .50 M2HB Browning machineguns with a high rate of fire but was not very powerfull. The M1936 Bofors have a great service during the war. It have a low rate of fire, but it was powerfull. Because this, the Americans will use this gun for equip a vehicles. Another M3 Halftrack was the T54E1 but it was very unstable when its fired. So there was again a neew for new vehicles. The solution was a vehicle wich will be followed by the M42 Duster and that was the M19 GMC based on the M24 Chaffee chassis. The turret was removed and replace by a nesw open turret with two shields. Because they moved the engine from the back to the front, it was possible to place the turret on the back. The guns are two 40 mm Bofors M1936 AA-guns. Only 285 were built.