With the 1950 introduction of the SW8 and SW9, EMD cataloged end-cab switchers in three convenient sizes: small (the 6 cylinder, 600 hp SW1), medium (the 8 cylinder, 800 hp SW8) and large (the 12 cylinder, 1200 hp SW9).
All three engines shared the same 44' frame. While the SW1 was distinguished by its shorter hood and large "porches" on each end, its more powerful siblings looked nearly the same, except for the single exhaust stack on the SW8 and dual stacks on the SW9. Contrary to popular belief, the "SW" in the model names did not stand for switcher. "S" stood for six hundred, the horsepower rating of the initial model, and "W" stood for welded frame, in contrast with the cast steel frames of earlier Electro-Motive switchers.
Weighing nine tons less than the SW9, the SW8 proved suitable for places where its larger brother couldn't go, especially on industrial properties and short lines. By the end of production in 1954, 309 SW8s had been sold to 48 U.S. class 1 railroads, short lines and industrial firms. An additional 65 engines were built by GM Diesel Canada for 10 Canadian operators.
The largest single purchase of SW8s, however - 41 locomotives - was by the US Army during the Korean War. The Korean National Railroad (KNR), built largely by the invading Japanese in WWII, fortunately used the same track gauge and knuckle couplers as American railroads. Thus the SW8s, the first diesels on the KNR, proved invaluable in transporting men and materiel from the staging areas at Pusan harbor toward the front lines and bringing wounded soldiers back to Pusan hospitals. Most of the locomotives were repatirated after the war and later served on stateside military bases. Two of the ex-Army units are still operating today at the Heart of Dixie Railroad Museum in Calera, Alabama.