In the 1930s, as the PRR had increased passenger service time tables, the trains became longer and heavier than a single K4s could handle, necessitating double-heading with a second engine.

The "Standard Railroad Of The World" made attempts to replace the 1737 and its classmates with larger, more powerful classes including: K5, S1, and the T1, none of which were successful; thus, the K4s continued hauling passenger trains until the Pennsylvania Railroad replaced steam locomotives with the increasingly-popular and less-costly diesel-electric locomotives in 1957.

The New York and Long Branch Railroad in South Amboy, New Jersey used the K4s to haul commuter trains.

When the famous electric Pennsylvania Railroad class GG1 would bring the trains from New York City's Penn Station, the K4s would take over the train and make the run from the South Amboy station to Bay Head, New Jersey.

1737 was originally slated to be preserved as part of the PRR's Historical Collection at a roundhouse in Northumberland, Pennsylvania.