Victorian Railways replaced track section repair gangs with statewide 'mobile gangs' during the 1960's. These gangs remained in districts long enough to complete track repairs and then moved on to another area. The workmen were housed in sleeper cars fitted with beds and kitchens. Toilets and bathroom facilities were provided at the camp sites.
Two surplus fixed wheel horseboxes were converted to 'mess cars' with the fitting of long tables for eating.
WM 1 was built as _FF_ 59 in 1905, to _F__ 31 about 1910 and to WM 1 in 1952. In 1969 it was recoded to _HD_ 231.
WM 2 was built as F 38 in 1910 and was converted to WM 2 in 1952. In 1959 it was fitted with the underframe of _Z__ 287.