In 1959 MLW finally decided to replace the 539 engine with the turbocharged 251C engine which generated 1000 hp. MLW put this engine under a similar car-body to that used for the S-12 and created the S-13, although the turbocharger exhaust stack was relocated from the rear to the front of the hood roof and the left-side bulge is absent. 49 units were purchased in 1959 and numbered 8500-8522 and 8600-8625. The latter units were equipped with MU control for operation in hump yard service, were heavier, had dual sealed-beam headlights, different gearing and traction motors, drop steps and MU hoses and cables at both ends. Most were subsequently repainted into the two CN logo schemes.
S-13s underwent a variety of modifications but not all units received a specific modification. There are thus several possible combinations. In the mid to late 1960s several 8600 units in Toronto were fitted with rotating beacons, had their bogies modified to go over the retarders and were modified to work as hump “mother” units with the S-3 slugs.
