The T-54 was developed by the Morozov design bureau at the Uralvagonzavod (Urals Rail-car Factory) in Nizhni Tagil, best known for its earlier efforts on the legendary T-34 of World War 2. The T-44 was closely followed by the T-54 which introduced two key improvements, a new 100mm gun and a new transmission. The T-54 itself was plagued with teething problems, mandating a senes of improvements which eventuallyculminated in the classic T-54A in 1951. The T-54 is the most widely produced member of this tank series, with some 35,000 built in the USSR, 5,500 in Poland and Czechoslovakia, and over 16,000 of the Type 59 derivative in the PRC.