On a sultry June day two switch crews are busy. The railway operations in the Port of Montreal were previously known as the National Harbours Board (NHB) Railway. The NHB obtained eight MLW S-3 switchers in 1951 to replace their 0-6-0 steam switchers, seven of which in 1941 had been received in trade from CN for the nine NHB English Electric boxcab electrics.