 Otherwise, the DD group was reclassed as either D1 or D2 as appropriate, for the most part without renumbering.Unlike with other renumbering projects, engines converted to D3 and renumbered did not have their previous slots immediately filled.In 1951, to make way for new J and R Class engines being ordered under Operation Phoenix, the remaining D1 and D2 engines were renumbered to the range 561-579 and 580-604 respectively, with D3 604 changing to 606.