All were assembled at a facility established by Clyde Engineering within Westrail's Forrestfield Depot to fulfill the contract.

The frames were built at Clyde's Somerton plant with other components manufactured at Kelso.

[5] The S class locomotives entered service in June 1998 hauling ore and mineral trains in South West Western Australia.

[9] In 2008, Rio Tinto ordered two standard gauge JT42Cs of the same design as the S class for the Weipa bauxite railway, numbered R1005 and R1006.

[10] R1005 remains in service today, while R1006 was withdrawn and scrapped following a collision in September 2019.