WOB type iron ore waggon WOB 31392 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 317 for Koolyanobbing iron ore operations, this waggon was converted to a WSM ballast hopper, then converted back to a WOB by WAGR Midland Workshops, and started life as a Comeng built Mt Newman Mining ore car in 1974. It was originally numbered 31391 by WAGR, on empty train 6418 at Binduli Triangle, 31st July 2010.