Caption: At 9 a.m. on Wednesday, May 1, 1968, CN Train 406 is just east of St. Basil, New Brunswick near Mileage 213 of the Napadogan Subdivision. The two almost new C-630Ms, 2022 and 2025, are en route to Moncton. During the night, they had traversed the hill and dale National Transcontinental route from Joffre near Quebec City to Edmundston. Nearly a decade later, that trip would take them across the Pelletier cut-off that linked the former NTR line directly to the water level route along the St. Lawrence River.

CN sampled four-axle second-generation power from both MLW and GMDL in the early 1960s in the form of C-424s, GP35s and GP40s. As with many railways, the translation of high horsepower to effective tractive effort through four traction motors did not prove overly successful. Hence, following demonstrations of UP C-630s and EMD SD40xs in 1966, CN shifted their orders to exclusively six-axle units between 1967 and 1972. MLW supplied two sample units, 2000 and 2001, in August 1967 followed almost immediately by an order for 42 additional C-630Ms. They rode on hi-adhesion trucks newly designed by Dofasco in Hamilton, Ontario, that featured a very short 11' 2" wheelbase. The MR-30 class units served primarily east of Montreal during their lifetime until CN replaced them on priority trains with GE Dash 8-40CM in the 2400 series beginning in 1990. As CN retired the units, the Cape Breton and Central Nova Scotia Railway obtained nine of these "Big Alcos," including the 2022, which uniquely became a parts source in Sydney, Nova Scotia.