 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 1940-1941.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.