The next step taken was the production of 400 TR-580/TR-77 tank and even if the local arms industry lacked the experience required to design and produce a medium tank from scratch the Communist government did not buy the license for the T-55 tank. The initial batch (the prototype and the first 10 tanks), officially known as the TR-77 tank ("Tanc românesc model 1977" Romanian Tank model 1977), was intended to use the Leopard 1 engine and, as a result, the hull was extended, having 6 instead of the usual 5 road wheels of the T-55 tank.