Template:LocoType/Alco-C-420

The Alco C-420 was a 2,000-horsepower B-B road switcher introduced in 1963 as part of Alco's Century series — a renamed and refined product line intended to signal a fresh start after the reliability difficulties of the 244-engine era and to compete more effectively against EMD and the rising GE. The Century designation replaced the RS/RSD nomenclature that Alco had used since the early road switcher era, and the C-420's designation followed the new format: C for Century, 4 for four axles, and 20 for 2,000 horsepower. The 251B prime mover produced 2,000 horsepower in a well-proportioned B-B package, and the Century series locomotives incorporated detail improvements to cab comfort, accessibility, and electrical systems compared to earlier Alco road switchers.

Approximately 130 C-420s were built across its five-year production run, purchased by a range of railroads including the Long Island Rail Road, Lehigh Valley, and several others with established Alco preferences. The Century series represented Alco's most competitive product offering in the 1960s, and the C-420 served its customers reliably in general freight and commuter service. The Long Island Rail Road's fleet of C-420s served in New York suburban commuter service for many years, giving the model a specific and well-documented operational identity. In O Gauge, the Alco C-420 is a transition-era road switcher subject for modelers focused on northeastern railroads and the Alco product line of the 1960s.