For the new passenger services with N cars, a new locomotive was placed into service.
The new locomotive featured Head End Power generator, cab at each end, and a V-12 engine block. The loco's were built at Somerton, Victoria between 1981 and 1984.
There were twenty-five units, numbered 451 - 475.
They replaced _B__, _S__, _T__ and _X__ locomotives.
From the late 1980's, the units were rostered on freight trains to increase utilisation.