 Built in the early 1950s by ALCO, the Katy had them rebuilt in the late 1950s by ALCO competitor, EMD, who rebuilt them with GP9 long hoods to make room for the larger EMD 567 prime movers.The Chicago and North Western Railway had a pair of RS-3ms that were rebuilt using ALCO components.These featured long hoods from ALCO RS-11 road switchers.