Two prototype four wheeled open wagons numbered GF13319 and 13320 were built in 1950. They were the prototypes for the GH class open wagons. However, the two prototypes did not last long and the underframes were used to build two ZF class brake vans (GH13320 became ZF440 whilst GH13319 became ZF441) in March 1953. The design was not repeated and the two vans were written off in May 1969 (ZF440) and January 1973 (ZF441). ZF441 is preserved at Bassendean.

The WAGR outline diagram is shown below.