Manufactured toward the final stages of WWII, the M40 self-propelled gun design employed a combination of proven M4 Sherman chassis components and the powerful 155mm "Long Tom" gun. It was a boon for the 8-man U.S. crews that deployed it, not least because of the serious mobility upgrade it offered over its towed artillery piece predecessors, and an impressive range of 23.5 kilometers using explosive rounds; stability when firing was provided by a large rear spade. A 460hp air cooled engine enabled a top speed of 38km/h. Production began in February 1945, and while it was officially adopted in May 1945 none of the 418 manufactured by the end of WWII saw action. Instead, this powerful SPG was deployed in the Korean War, in which it provided long range bombardments of enemy positions.