In the 1979 recoding, the _JX_ wagons ( numbers 1 to 108 ) were reclassed to VPCX.
VPCX 109 to 158 were built new during 1981/1982.
Traffic originated from a cement plant at Fyansford, near Geelong. Melbourne was a major destination. Cement powder was also transported from Fyansford for the construction of the new Parliament House at Canberra.
The 'Blue Circle' cement group built a holding depot at Somerton. This allowed for road distribution in the northern area. It had been anticipated that cement powder from offshore sources would ultimately be purchased; by ship to Sydney, then rail to Somerton.
To segregate the different air pressure discharge groups, the class was split into three groups. About 1992, the group 59 - 108 began being relettered VPAX. In 1996, the group 109 - 158 began being reclassed VPBX.
From 1992 the VPCX wagons numbered 59 - 108 were being relettered to VPAX.
From 1996 the VPCX wagons numbered 109 - 158 were being relettered VPBX.