Walla Siding, comparison between two empty BHP ore waggons with the tapered floor design. 4507 was built by Transfield WA in in 1976 in an order for eighteen waggons, while 4260 is a Goninan WA build from an order of one hundred and twenty-six waggons using 3CR12 stainless steel in an effort to eliminate internal painting and reducing wear on the waggon body, these were designated HC7081. 20th of June 2011.