Serbian tank that had leftover Hellcat from WW2, mated with a T-55 from when they (Czechosovakia) were part of the Warsaw Pact. When you lose your major arms supplier and your country's in a civil war, you make do with what you can.
There was a resin conversion for it, but most just sacrificed an M18 Hellcat since neither kit was particularly good (AFV Club or Academy M18).
http://www.greatmodels.com/~smartcart/cgi/display.cgi?item_num=PS35234