 With mainline electric and diesel-electric locomotives already on order, Victorian Railways' design team opted for an updated, gauge-convertible K class as what would turn out to be their final steam locomotive design.The key problem with the K class design was the placement of the firebox between the locomotive's frames and rear driving wheels, making conversion to a narrower gauge impossible without radical redesign of the firebox.A previous attempt to develop a gauge convertible K class, the N class, utilised a 2-8-2 wheel arrangement and positioned the firebox above the frames and behind the driving wheels.