Complex sentence: In 1943 Becker began converting the Hotchkiss H35 and H39 light tanks, which had carried a 37 mm gun, and refit them to mount a 7.5 cm PaK40 anti-tank gun or 10.5 cm leFH16 howitzer assault gun.
Split into simpler sentences: In 1943 Becker began conversion of the Hotchkiss H35 and H39 light tanks, which had carried a 37 mm gun. He refit them to mount a 7.5 cm PaK40 anti-tank gun or 10.5 cm leFH16 howitzer assault gun.