Boston & Maine 690 (ex Illinois Terminal 2301) with Train EDRJ (East Deerfield–Rotterdam Jct) about to enter Hoosac Tunnel.

(The original uploader was Gp38 at English Wikipedia., CC BY 2.5 <>, via Wikimedia Commons)



The SD39 is a model of 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division between August 1968 and May 1970. 54 were built for American railroads.

In 1966, EMD replaced all their old models with new ones having the new 645 diesel. These included six-axle models SD38, SD40, SDP40 and SD45; the SD39 was added in 1968. All shared standard components including the frame, cab, traction alternator, trucks, traction motors, and air brakes. The difference was the power output: SD38 = 2,000 hp (1,490 kW) from a non-turbocharged V16, SD39 = 2,300 hp (1,720 kW) from a turbocharged V12, SD40 = 3,000 hp (2,240 kW) from a turbocharged V16, and SD45 = 3,600 hp (2,680 kW) from a turbocharged V20. The SD39 had the smallest prime mover and therefore had the most unused space above the frame, inside the hood between the main generator and electrical cabinet, and outside in large end "porches".



A variant was the SDL39, ordered by the Milwaukee Road. Shorter and lighter than a stock SD39, these minimized weight per axle.


Southern Pacific EMD SD39 5320 at El Centro, California, June 30, 1970. Photographer: W. E. Harmon.

(Craig Garver, Public domain,



SP 5320 is shown here just two months after delivery. This engine was built in April, 1970, part of the railroad's second order for eight units, SP 5318-5325. There were just 54 SD39's built, 26 for SP and 20 for Santa Fe, six for the Illinois Terminal, and two for the Minneapolis, Northfield & Southern. Milwaukee Road bought ten special lightweight versions, the SDL39. SP and Santa Fe used them for slow speed high tractive effort duties. SP's were for the Bakersfield-Los Angeles Freight Pool for use on Tehachapi and Beaumont passes. Santa Fe's were used from El Paso North to Denver and East to Kansas City, especially on the Carlsbad, New Mexico, to Galveston unit molten sulfur trains.


Original owners

Railroad Quantity Road numbers Notes
Atchison, Topeka and Santa Fe Railway 20 4000-4019 All to BNSF and then sold to LTEX in 2010.
Illinois Terminal Railroad 6 2301-2306 4 went to Guilford Rail System, all have been scrapped.
Minneapolis, Northfield and Southern Railway 2 40-41 No. 40 as of August 25, 2021 used by Progressive Rail, Inc., No. 41 has been scrapped.
Southern Pacific Transportation Company 26 5300-5325 To Union Pacific and then to leasers and shortlines.
Total 54

Dash 2 Series

On January 1, 1972, EMD debuted Dash 2 models. No official SD39-2s were built, though the model was catalogued. Some SD39s were rebuilt to Dash 2 specifications, however, and received the SD39-2 designation. Also, BNSF has re-designated some of their SD40-2 locomotives as 'SD39-2s'; it is unknown at the time of this writing what mechanical changes have been made to these locomotives.


FEPASA 2360, an SD39-2M, in 2011.

(Felipe Tapia, CC BY 3.0 <>, via Wikimedia Commons)


Disposition of units

Some of the SD39 model were subsequently resold to other operators including:

  • FEPASA 2360, an SD39-2M, in 2011.
  • FEPASA - 14 SD39-2s numbered 2350-2363; the last seven, 2358–2363, rebuilt as SD39-2M by NRE.
  • TRANSAP - 4 SD39-3M locomotives rebuilt by MPI de Mexico numbered D2301-D2304.



Type and origin
Power type: Diesel-electric
Builder: General Motors Electro-Motive Division (EMD)
Model: SD39
Build date: August 1968 – May 1970
Total produced: 54
Configuration: AAR C-C
Gauge: 4 ft 8+1⁄2 in (1,435 mm) standard gauge
Driver diameter: 40 in (1,016 mm)
Length: 65 ft 9+1⁄2 in (20.05 m)
Prime mover: EMD 12-645E3
Engine type: V12 diesel
Aspiration: turbocharged
Cylinders: 12
Locomotive brake: Independent air; optional: dynamic brakes
Train brakes: Air, schedule 26-L
Performance figures
Power output: 2,300 hp (1,720 kW)
Locale: United States