Very similar to the StuG III Ausf A with some minor chassis variations. Was built on the PzKpfw III Ausf H chassis.
New superstructure was main change. The gunner's direct vision sight was eliminated. The gunner's hatch was redesigned so that the gun sight could be raised beside it while the hatch remained closed. Some of the StuG III Ausf Ds were modified to be a commander's vehicle by adding a pannier to the right side of the superstructure.