This is construction #4, another saturated steam loco with the large water and oil tanks. The large cylinder above the front truck is the air reservoir for the air brakes. Mounted above it out of sight under the running board is a flat coil of pipe for cooling the air. This was standard on the Willamette, but I have not seen a factory air cooler on any other geared locomotive. The front view has good lighting showing the detail of the locomotive well.