The M40, M43 used an M4A3 (Sherman) chassis that was widened and used the high volute suspension springing. The engine was moved to the front and a spade was placed in the rear to help absorb some of the recoil. Intended to be used well behind the front lines so no protection for the crew was provided. An intrisic componned of the very effective -and much dreaded by the germans- american artillery.