On 4 January 1944, the Panzerkomission approved of the PzKpfw III/IV, with a combination of the PzKpfw III and PzKpfw IV chassis. The Maybach HL-120TRM, having been successful during the ongoing Second World War, was selected as the engine for this new project, and was connected to the SSG-77 transmission. The most striking change was the use of a box drive with large wheels, with a hydraulic pivoting device tower.