Caption: CP S10 6603, one of the local Toronto-area MLW switchers based out of John St. Roundhouse, sits near the yard office at CP's Lambton Yard in West Toronto, just above the Runnymede Road overpass. In the distance is CP caboose 436468, an old wooden "van" still with its tongue-and-groove siding and a rare paint variation (multimark painted on the cupola end, common practice on steel vans but very rare on wooden ones).

The MLW S10 was a "new" model introduced by MLW in 1958, but was basically identical to the later-carbody 660-horsepower S3 model that CP had been purchasing. CP opted for an order of 13 units, numbered 6601-6613. MLW later changed their 660hp switcher design to the S11 (which shared a common body style with the S13/RS23 units).

By the 1980's, the old steam-era Alco/MLW switchers were considered outdated and underpowered, and CP began to rebuilt GMD-built GP7/9 and SW units to replace most in yard and local service. 6603 was retired in early 1983, and scrapped at Angus Shops in Montreal.

Stan F. Styles photo, Dan Dell'Unto collection slide.