The ČSD also bought the heavy Soviet M62 diesel freight locomotives. Between 1966 and 1979 they received a total of 599 of these locomotives, most of which were listed as T 679.1. In Czechoslovakia they were nicknamed “Sergei”. 25 were intended for cross-border traffic to the Soviet Union in today's Ukraine. These had a gauge of 1,520 mm and were designated T 679.5. Some of these were already converted to standard gauge in the 1970s. In the 1990s, they gradually became superfluous in Slovakia and the Czech Republic and were scrapped or sold, with a double-digit number coming to Germany. The last assignments for the ČD were in 2002. 