In 1970 fifteen WSH class standard gauge ballast hoppers numbered 30501-30515 were converted to class XM. Weekly notice 40 of 1970 explains some of the limitations of using converted standard gauge wagons. XM ballast hoppers, 15 of these in use on Esperance branch, fitted with Alliance couplers at sg height of 2ft 11in above rail level, 4 special type transition pieces manufactured, 2 used on rake, 2 spares with driver in charge Esperance. In 1977 30501 was temporarily converted back to WSH as were 30502, 30505, 30506, 30508, 30509, 30510, 30511, 30512, 30514, 30515 in 1981.

The WAGR outline diagram for the XM class is shown below.

Four of these hoppers were modified to carry gravel ballast by ARG and reclassified XMG (30501, 30502, 30503 and 30505).