1946 - double-worm drive, horizontal motor, smoke lamp
1947 - single-worm drive, resistive smoke unit, protruding e-unit lever.
1948 - 2671W 12 Wheel tender replaced the 8 wheel 671W. The 4 flanged drive wheels were zinc with blackened steel rims where as the blanks were sintered iron without rims.
1949 - All wheels sintered iron without rims