Iran and Bangladesh have been upgrading their Chinese Type 59 (copies of the Russian T-55) tanks to produce Type 59Gs. The two nation's Type 59Gs are not identical, but they both feature a new turret, equipped with a larger (125mm in Iran, 120mm in Bangladesh) gun and the addition of ERA (Explosive Reactive Armor) to the hull and a modern fire control system. The 300 Bangladeshi Type 59Gs also have a more powerful Ukrainian 1,200hp engine.
The most recent model in Chinese service is the Type 59D, which was introduced in the 1990s, adding ERA armor, a 105mm gun and better fire control. The Chinese have built nearly 10,000 Type-59s, with the basic model weighing 36 tons, having a 520hp engine and a top speed of 50 kilometers an hour. The more recent models are closer to 40 tons, or more. Production of the Type 59 halted in 1980, but many have been upgraded since then.