In 1970 and 1971, six new trailer carriages were built as prototypes for the next fleet (the Hitachi trains). These carriages were long, compared to of the earlier carriages, and were equipped with the mechanisms for power-closing doors, the first such use in Melbourne. However, it was not until the following year that a complete (4-carriage) train was used this way, after conversion of some motor carriages. These carriages were converted into H type carriages, for use in LH sets with V/Line, in the mid 1980s.