Class U-3b 0-8-0 switcher No. 7643 rests at an unknown location and date in this view supplied by Wayne Koch. The U-3b class had a grate area of 47 square feet, 2775 square feet of evaporative heating surface, and 640 square feet of superheating surface; for other dimensions consult the commentary for No. 7640. The U-3 class was a USRA design first ordered during World War I that went on to become the Central's standard heavy switcher throughout the system. This locomotive, originally numbered 243, was retired and scrapped in 1953.