The design was modified in 1925 into the N class 2-8-2, in response to a new Victorian Railways policy that all new locomotives be capable of conversion from to in the event of the Victorian Railways network being standardised. The K, with its firebox mounted between the frames, was unsuitable for standard gauge conversion. The K class proved to be such a successful locomotive that, despite not being gauge convertible, a further 29 units were ordered just before World War II, being delivered between 1940 and 1941. The first of the new engines was 140, quickly renumbered 150 then followed by 151 to 178; the original ten engines were also renumbered 140–149. In 1942 a further order was placed for an additional 21 engines, which would have brought the fleet total to 61 engines. However, only five of this batch - 179 to 183 - entered service during 1943, and construction was halted until after the end of hostilities when work resumed on engines K184 to K192. The remaining engines were never built.