As early as 1934/35, General Heinz Guderian envisioned two basic types to act as the main equipment for the future German Panzer Divisions. The first vehicle was to be armed with anti-tank gun and two machine guns and second one was to be a support vehicle armed with a larger calibre gun. The first one eventually became known as Panzerkampfwagen III, which was to be a standard tank for the three light companies of a tank battalion. The second one became known as Panzerkampfwagen IV.With the appearance of the T-34, rearming the Panzer III with a more powerful L/60 50mm gun was prioritized. The Ausf J version had this longer gun, thicker armor, and some simplified features; in addition, the hull was lengthened. This version was available throughout 1942 and into 1943.