In an attempt to increase tank output in summer of 1941, the Kharkov Tractor Zavod (»KhTZ« or »XTZ« in cyrillic) installed one inch armour plates around the STZ-3 that was already in production since 1937. On top came a 45 mm gun turret resulting in the new KhTZ-16. However, only a mere 50-60 samples were finished until the Germans captured KhTZ in October of 1941.
The STZ-3, built at the Stalingrad Tractor Zavod (»STZ« or »CTZ« in cyrillic) as well, was a typical example of an agricultural design (mis)used for military purposes.
With a huge air cleaner and wide tracks it was well suited to the Russian climatic conditons and developed into a real work horse capable of towing even the largest guns.
Two types of cabs existed, with slanted windscreen / open sides and with vertical windscreen / side doors.
Tens of thousands were built throughout the war and beyond, and many were captured and used by the German invaders.