The 155 mm Gun Motor Carriage M40 was a US self-propelled artillery vehicle built on a widened and lengthened Medium Tank M4A3 chassis but with Continental engine and with HVSS (Horizontal Volute Spring Suspension) that was introduced at the end of the Second World War. Equipped with a 155 mm M2 gun, it was designed to replace the earlier M12 Gun Motor Carriage. Its prototype designation was the T83, but this was changed to the M40 in March 1945.