 The RSD-15 could be ordered with either a high or low short hood; railfans dubbed the low short hood version "Alligators", due to their unusually long low noses.A single example of the very similar model RSD-17 was built by the Montreal Locomotive Works in 1957.After demonstrating on the Canadian Pacific "(as #7007)", the Canadian National "(as #3899)", and the Pacific Great Eastern "(as #624)", the locomotive was purchased by the Canadian Pacific "(as #8921)".