There are several variations of the SD40-2 such as the SD40T-2s (Informally: T for tunnel motor; the actual EMD designation is "SD40-2 With Cooling System Modification", as stated on this model's EMD manuals) bought by the former Southern Pacific, and Denver and Rio Grande Western railroads; now operated by Union Pacific. The SD45 tunnel motor equivalent, the SD45T-2 model, was also utilized by Southern Pacific. Many tunnel motors were rebuilt and sold second-hand to a handful of American shortlines including, Bessemer and Lake Erie, Illinois Railway and Missouri and Northern Arkansas, as well as Canadian shortline Goderich-Exeter Railway. There is the SD40-2W (W for the 4-Window Safety Cab) bought and operated by the Canadian National railway. High-nosed versions of the SD40-2 were bought by Norfolk & Western, & Southern Railway. These units are now operated by the Norfolk Southern Railway (Resulting merger of N&W and Southern Railway). A narrow gauge version produced for Ferrovia Central Atlantico in Brazil is the BB40-2.