Based on the narrow-gauge locomotive ТУ6 (TU6), the ТУ6А was built in Kambarka from 1973, which now had 200 instead of 90 hp. Like this one, it had two bogies with mechanical power transmission. The TU6A was placed below the more powerful ТУ4 with hydraulic power transmission. Externally they were initially almost identical until the visual appearance was changed in later machines. The number reached 3,915 by 1988, making it the most widespread narrow-gauge locomotive in the Soviet Union. Many were used in industrial plants, but one made it to the children's railway in Yaroslavl. 