Editing EMD SDP45 (section)

==Original owners==
The [[Southern Pacific Railroad]] ordered their ten on May 9, 1966, with the units being placed in service between May 24 and July 26, 1967, initially on the ''[[City of San Francisco (train)|City of San Francisco]]'' between [[Oakland]] and [[Ogden, Utah|Ogden]], and eventually used system-wide. As built, each unit carried {{convert|2500|USgal}} of fuel and {{convert|3000|USgal}} of steam generator water in a partitioned underframe tank. The steam generator was a [[Steam generator (railroad)|Vapor Model OK-4740]]. SP's units had Pyle National Gyralights on the leading end, came with Nathan P-3 [[Train horn|horns]], and cost $317,156 each (SP's straight [[EMD SD45|SD45's]] from the same period cost $290,788 each). Ordered with 62:15 gearing with the overspeed set at {{convert|72|mph|abbr=on}}, the gearing was changed to 60:17 (overspeed at {{convert|83|mph|abbr=on|disp=or}}) during 1968–1969. All except 3201 and 3207 would eventually be re-geared back to 62:15 once they entered [[Commuter rail in North America|commuter service]]. 

After [[Amtrak]] took over long-distance routes in 1971, various units were leased to Amtrak for West Coast service (primarily on the [[Coast Starlight]]) until Amtrak purchased their [[EMD SDP40F|SDP40F]] locomotives, while the rest were used in freight service and on Company specials. Beginning in 1973 the SDP45s were used for [[Peninsula Commute|commuter service]] on the [[San Francisco]] [[Peninsula Commute]], replacing the [[FM H-24-66|Fairbanks-Morse Train Masters]]. SP's commuter service was demanding work and the locomotives required electrical modification to meet those demands. A "Passenger Start" switch was installed inside the cab electrical cabinet; in the "COMM" position the units were held in Parallel, in the "FRT/PASS" position normal transition was made. They stayed on the commute route (often working in freight service on weekends) until 1985 when [[Caltrain]] equipment arrived, and they were placed into freight service until their retirement, initially working out of [[Roseville, California|Roseville]], then in local and hauler service in the [[Los Angeles Basin]]. All were retired between 1986 (3208) and 1990 (3204) and sold for [[scrap]].

The [[Great Northern Railway (U.S.)|Great Northern Railway]] purchased eight SDP45s in 1967 to replace [[EMD F-unit|F-units]] on the ''[[Empire Builder]]''. Normally paired back-to-back, they were also used singly leading [[EMD F-unit|F-units]]. These joined six smaller [[EMD SDP40|SDP40]] locomotives ordered in 1966 for the [[Western Star (train)|Western Star]]. After the startup of [[Amtrak]] in 1971, [[Great Northern Railway (U.S.)|Great Northern Railway]] successor [[Burlington Northern Railroad]] converted all fourteen SDP locomotives to freight service.

The [[Erie Lackawanna Railroad]] ordered 34 SDP45s in 1969 and 1970. Intended only for freight service, these units had standard (angled) long hood ends, and the extra space aft of the radiators had concrete ballast where a passenger unit would have a steam generator and venting. Their longer frames permitted a larger fuel tank which gave the locomotives a greater range between fuel stops.  EMD later redesignated these as SD45Ms.<ref>{{Cite book|last=Schafer|first=Mike|url=https://www.worldcat.org/oclc/38738930|title=Vintage diesel locomotives|date=1998|publisher=Motorbooks International|isbn=0-7603-0507-2|location=Osceola, WI|pages=39|oclc=38738930}}</ref>

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