The EMD F3 was a 1,500-horsepower (1,100 kW) B-B freight- and passenger-hauling diesel locomotive produced between July 1945 and February 1949 by General Motors’ Electro-Motive Division. Final assembly was at GM-EMD's La Grange, Illinois plant. A total of 1,111 cab-equipped lead A units and 696 cabless booster B units were built.
The F3 was the third model in GM-EMD's highly successful F-unit series of cab unit diesel locomotives, and it was the second most produced of the series. The F3 essentially differed from the EMD F2 in that it used the “new” D12 generator to produce more power, and from the later EMD F7 in electrical equipment. Some late-model F3's had the same D27 traction motors, along with the heavier-duty electrical cables, used in the F7, and were unofficially referred to as F5 's.
The F3 used a 16 cylinder 567B series diesel engine developing 1,500 hp (1.1 MW) at 800 rpm. The 567 was designed specifically for railroad locomotives, a supercharged 2 stroke 45 degree V type with 567 cu in (9.29 L) displacement per cylinder, for a total of 9,072 cu in (148.66 L). A D.C. generator powered four traction motors, two on each Blomberg B truck. EMD has built all of its major components since 1939.