WOB type iron ore waggon WOB 31387 is one of a batch of twenty five built by Comeng WA between 1974 and 1975 and converted from Mt Newman high sided waggons by WAGR Midland Workshops with a capacity of 67 tons with fleet number 312 for Koolyanobbing iron ore operations. This waggon was also converted to a WSM type ballast hopper by re-fitting the cut down top section and having bottom discharge doors fitted, converted back to WOB in 1998, loaded with fines in West Kalgoorlie, 2nd June 2010.