About 1987/1988, two hundred and fifty eight VOBX / VOCX wagons were reclassed to VOFX. These open wagons were used to transfer superphosphate from Geelong to country areas for agricultural use.
Up to the 1980's, fixed wheel open wagons coded _GY_ were used for this traffic.
All the VOFX wagons were of the corrugated side type, fitted with tarpaulin stanchions for foul weather cover. Low numbered VOFX between 3 and 77 were all plain sided wagons rebuilt to corrugated type.
Between 1994/1995 most of the wagons were reclassed to NRC as ROBX, RKUX and RKCX.