Since CN uses a GP9RM+slug set for power, it's only natural that they get to lead. Here the switcher is bringing in 4 bulkheads from the nearby Industrial park. The way the photo is cropped however, it looks like a much bigger train.
Note the headlight on the slug, these are unique to the S-3 converted models, unlike the GP9's and YBU-4s which are rather flat.