The superstructure was redesigned in early 1944 for the fourth series,
which used the chassis and HL120TRM112 engine of the Ausf. J, and was in
production between June 1944 and March 1945. It featured a redesigned
gun collar, as well as a general reduction in height of the
superstructure. This redesign also introduced a ball mount in the front
superstructure for a MG 34 machine gun with 600 rounds. The vehicle commander's position was modified to use the cupola of the Sturmgeschütz III Ausf. G, which could mount a machine gun for anti-aircraft defense.