The Susquehanna dieselized early, acquiring a fleet of Alco S2's and RS1's that put steam out to pasture by the late '40s. The NYS&W demanded a lot of these 1000-hp units. They would often overheat, and many of the photos of them show all of the hood doors open as the crews tried to keep the prime movers cool.
In 1962, the Susie-Q took delivery of three GP18's from EMD. The previous year, the Susquehanna's freight volume took a hit with the abandonment of the Lehigh & New England, so many of the Alco's were set aside in Little Ferry.
The retired units remained as derelict parts sources for the few active Alco's.
When Bicentennial fever overtook the railroads, the NYS&W chose one of the survivor RS1's to be their representative. Four years after our nation's 200th birthday, 252 is still wearing her patriotic garb.