In April of 1942, the Italian command came up with the idea to develop an assault tank destroyer with a 105 mm howitzer on the chassis of the Carro Armato P 40 heavy tank. The project was developing rather slowly, so instead, officials decided to use the improved chassis of the mass-produced Carro Armato M 15/42 for a new vehicle. This vehicle featured a 105 mm howitzer with a length of 23 calibers. The prototype was completed in January 1943, and it became the first Italian vehicle to be partially welded. The serial model, designated Semovente da 105/25 M43, received a 25 caliber gun and a newly designed hull and cabin. Before Italy's capitulation on September 8, 1943, 30 vehicles had already been manufactured and sent to military units. Later these vehicles all fell into the hands of the Germans, who set up and continued production. Between 1943 and 1944, 121 more vehicles were produced.