THE RS-18 DIESELS WERE ROAD SWITCHERS IN COMMON USE FROM COAST TO COAST ACROSS CANADA FROM 1954 UNTIL THE EARLY 1980'S IN BOTH FRIEGHT AND PASSENGER SERVICE. MONTREAL LOCOMOTIVE WORKS (MLW) DEVELOPED THE RS-18 DESIGN BY UPGRADING THE 1600 HORSEPOWER RS-10 DESIGN WITH AN 1800-HORSEPOWER ENGINE AND, BETWEEN 1957 AND 1968, BUILT 351 RS-18 LOCOMOTIVES FOR EIGHT CUSTOMERS: CANADIAN NATIONAL(2225), CANADIAN PACIFIC (72), PACIFIC GREAT EASTERN (29), ROBERVAL & SAGUENAY (2), AND SEVERAL MINING COMPANIES (23) ALTHOUGH RS-18 DIESELS WERE BASICALLY EXTERNALLY INDISTINGUISHABLE, THEY HAD NUMEROUS VARIATIONS IN DETAILS SUCH AS AIR FILTERS, DYNAMIC BRAKES, FUEL TANKS, STEAM GENERATOR AND TRUCKS.