WO type iron ore waggon WO 31297 is one of a batch of fifteen built by WAGR Midland Workshops between July and October 1968 with fleet number 176 for Koolyanobbing iron ore operations, with a 75 ton and 1018 ft³ capacity, on loaded train 7415 at Binduli Triangle, 31st July 2010. This unit was converted to WOG for gypsum in late 1980s till 1994 when it was re-classed back to WO.