WFN 601-604 were built in 1975 and were followed by WFN605-610 in 1976. They were all rebuilt as WGL class wagons over a period of years. There were four conversions in 1979 (WFN 604, 605, 608, 610 became WGL 634-637) and a further five in 1984 (WFN 601, 603, 609, 602, 606, 607 became WGL 638-643).