The M4A2 Sherman was similar to the M4, with welded hull and cast turret, but was powered with twin GM 6-71 diesel engines. This was the only diesel engine version of the Sherman tank to see service in large numbers. Having a diesel engine, the M4A2 version`s engine deck and back end is noticeably different from all others Shermans. The early production model had the 75mm gun M3 in the M34 gun mount and vision slots in the front armor plate. The gun mount was later replaced by M34A1 gun mount, which featured a direct telescope. Some versions were armed with 76mm gun. In later productions, the return rollers were moved to the rear of the bogie mount and suspension was of the horizontal volute spring type. The M4A2 saw action in the European and Pacific theaters, and was mainly used by the US Marines and lend lease to the Soviet Union, British, and Free French. Over 8000 M4A2 were produced during the middle of World War II.