 The DD design was adapted into a 4-6-2T tank locomotive for suburban passenger use, the DDE (later D4) class.They were the most numerous locomotive class on the VR, with a total of 261 DD and 58 formula_1 locomotives built.By 1900, Victoria's express passenger locomotive fleet was almost exclusively made up of 4-4-0 designs of the Old A, New A, and the most recent AA class.