• Builder: ALCO in 1941.
• Horsepower: 1000.
• Engine: One (1) 6 cylinder four ­stroke diesel.
• Weight: 230,000 pounds

The S­2 (the "S" stands for "switcher") was the American Locomotive Company's most successful diesel­ electric locomotive: between 1940 and 1950, 1,505 were built, 1,465 at ALCO's works in Schenectady and 40 at its subsidiary the Montreal Locomotive Works in Canada, this locomotive was built by ALCO in 1941.

The S­2 was the 1000 hp outgrowth of a series of prototype and production end ­cab switchers built by ALCO during the 1930s (the S­1 was the 660 hp version). Sinking the 539 engine into an opening in the center of the underframe allowed reduction of the hood height by 2 foot 3 inches, improving crew visibility and bringing the design into line with its main competitors built by EMD and Baldwin. The radiator assembly was also relocated to the front of the hood, and the generator was reversed to keep short piping runs to the radiator assembly. The new design had excellent low speed performance under heavy loads, and proved highly competitive in the market in the 1950s.

No. 1 was one of 23 S­2 units built for the U.S. Department of Defense by ALCO. It was originally numbered 7102, and worked at the Richmond Quartermaster Depot in Virginia.   In the late 1970s, it was one of three U.S. Army S­2s transferred to the NASA Railroad at the Kennedy Space Center in Cape Canaveral, Florida.   It was used to move spacecraft components and chemical fuels on the Space Center property.

This locomotive is not fully operational and was occasionally used to position rail equipment . The locomotive sustained damage to its windows during Hurricane Andrew in 1992. It was in operating condition when stored.