The Alco S4 were 1,000 horsepower diesel electric switcher locomotives produced by Alco and Canadian licensee Montreal Locomotive Works. This locomotive was powered by an Alco 539 turbocharged 6 cylinder diesel engine and the S4 has standard AAR type A switcher trucks. Alco's 1,000-HP S4 switcher was the fourth entry in the company's highly successful "S" series of diesels. Their sturdy construction and ease of maintenance made them popular with a wide variety of railroads.
Operating dual directional headlights
Die-cast fuel tanks and underframe
Die-cast gear tower
E-Z Mate Mark II couplers