Route of the Rockets By Brian Schmidt | May 17, 2021 | Last updated on August 8, 2025 Email Newsletter Get the newest photos, videos, stories, and more from Trains.com brands. Sign-up for email today! Get Updates Route of the Rockets The 1,600-hp Alco RS3 was an all-time best-selling road switcher with more than 1,200 built from 1949 to 1956. Rock Island No. 492, built in 1951, operated in Chicago area commuter service. Rock Island photo