For the transport of motor car bodies between Melbourne and Adelaide, a bogie transport vehicle was built in 1958. It was built on the underframe of a scrapped swing door carriage and featured skeletal sides and car body mountings. The vehicle entered service as AA 1.
This vehicle was most interesting as it featured steam engine tender bogies and was built on a carriage underframe. The carriage was _B__ 144, built in 1902 as _AA_ 4 ( 2nd ), lengthened in 1909 and recoded to A 3 in the 1910 recoding.
By 1960, the original motor body transport concept had been revised to roll-on, roll-off, with a mobile ramp placed at one end for loading/unloading. The deck had been modified to suit drive on vehicles.
In 1960, thirteen more car body transports were converted from scrapped carriage underframes. These were AA 2 - 14. During 1961, eight more transports were built: AA 15 - 22.
In 1961, the class was recoded to AF. This required the fitting of roller bearing bogies and made them available for high speed trains: 60mph/100km/hr.
Betwen 1963 and 1965 all the vehicles were modified for bogie exchange and reclassed to _AX_, numbers 1 - 22.