Daimler-Benz AG used the chassis and running gear of its recent Panzer III medium tank as a basis for the new vehicle. Prototype manufacture was passed over to Alkett, which produced five prototypes in 1937 on Panzer III Ausf. B chassis. These prototypes featured a mild steel superstructure and a Krupp short-barrelled, howitzer-like in appearance, 7.5 cm StuK 37 L/24 cannon. Production vehicles with this gun were known as Gepanzerte Selbstfahrlafette für Sturmgeschütz 7.5 cm Kanone Ausführung A bis D (Sd.Kfz.142).