In 1974 three surplus SCX_ wagons had the cable drum cradles removed.
The three new flat wagons were classed SX; numbers 1, 2 and 3. They had been converted from SCX 2, 4 and 1 respectively.
In 1976, SCX 5 was similarly converted to SX 4.
SX 2 was out of service by 1980 and was converted to wheel carrier, HR 22, in 1981.
SX 3 was placed out of service in 1980 and was converted to bogie carrier HR 148.
In the 1979 recoding the class was relettered to VFEX.
The VFEX wagons were 1 and 4.
VFEX 1 was out of service and stored by 1991.
VFEX 4 was out of service during 1981. It was used as a replacement underframe to a VTQY tank wagon in 1983.