EMD SD45R

The EMD SD45R was a rebuild from EMD SD45 diesel locomotives that were originally built between August 1966 and January 1970 for the Southern Pacific Transportation Company, but were rebuilt by the Southern Pacific themselves under the Southern Pacific's M-99 rebuild program between 1979 and 1985.

History
Between August 1966 and January 1970, the Southern Pacific Transportation Company had ordered a total of 317 EMD SD45 locomotives from Electro-Motive Division as they were considered by the Southern Pacific themselves as the flagship of its locomotive fleet.

But there was an issue with the EMD SD45, the locomotives had some teething problems mainly by their massive twenty-cylinder prime movers that were prone to crankshaft failures from the engine block flex. Though it produced 600 hp more when compared to the EMD SD40's 16-645E3 prime movers, some railroads that were using EMD SD45 locomotives had felt that the extra horsepower wasn't worth it, even after EMD strengthened the block to eliminate the crankshaft failures. At low speeds, when tractive effort was adhesion-limited, the EMD SD45 provided no advantage over the EMD SD40.

As a result of all these issues, the Southern Pacific Transportation Company had rebuilt a total of 167 EMD SD45 units into what had become the EMD SD45R and renumbered them 7400 through 7566 at their own Sacramento Shops under the Southern Pacific's M-99 rebuild program.

Most of them in their SD45 form were classified by the Southern Pacific as EF636-1, EF636-2, EF636-3, EF636-4, EF636-5 and EF636-6, but when they were all rebuilt under the Southern Pacific's M-99 rebuild program, they were classified as EF636LR-1, EF636R-2 and EF636LR-3.

In 1996, Southern Pacific and its parent company, Rio Grande Industries had merged into Union Pacific and most of the EMD SD45R units had lasted into the days of Union Pacific until all of them were retired between 1997-2001 and some were given to Montana Rail Link, some were sold to leasing companies and some were sold for scrap. Nine locomotives were sold to the National Railway Equipment Company where they were rebuilt with 5-foot 6-inch gauge trucks, reclassified as an EMD SD40-3MP and sold to MRS Logística in Brazil.

One unit is preserved: Southern Pacific 7457 is a static display at the Utah State Railroad Museum.