EMD GP39X

The EMD GP39X was a specialized variant of the GP39 family produced by General Motors Electro-Motive Division exclusively for the Southern Railway. All six units were built to Southern Railway's specifications, which included the railroad's characteristic high short hood configuration, a design preference that Southern maintained across much of its diesel fleet. The GP39X represented a relatively small production run, reflecting the niche nature of the turbocharged mid-range road switcher concept within the broader diesel locomotive market of the era. In 1982, well into the tenure of Norfolk Southern, which had absorbed the Southern Railway, the six GP39X units were sent back to EMD to be upgraded to GP49 standards at Norfolk Southern's request. This refurbishment extended the operational lives of the locomotives considerably and brought their performance characteristics in line with a more contemporary EMD platform. Norfolk Southern continued to operate the units until 2001, when the locomotives were retired from freight service. Following their retirement from Norfolk Southern, the six former GP39X units found a second career in commuter rail service. Tri-Rail, the South Florida commuter railroad, acquired the locomotives and had them further modified to include head end power equipment and a lowered short hood, the latter alteration departing from the original Southern Railway high hood configuration. These changes made the units suitable for hauling commuter passenger equipment, giving the GP39X a legacy that extended across both freight and passenger operations.

The GP39X was rated at 2,600 horsepower, a figure that distinguished it from the standard GP39, which produced 2,300 horsepower using a turbocharged 12-cylinder EMD 645 prime mover. The additional output of the GP39X placed it between the GP39 and the more powerful road locomotives of the period, making it a capable but unconventional choice within EMD's product lineup. Like other members of the GP39 family, the locomotive rode on a four-axle Bo-prime Bo-prime wheel arrangement, providing a balance of tractive effort and axle loading suited to a wide range of track conditions encountered on the Southern Railway system. The subsequent upgrade to GP49 standards in 1982 involved modifications that brought the locomotives' mechanical and electrical systems closer to the specifications of the GP49, a 2,800-horsepower turbocharged locomotive that EMD had introduced as part of its second-generation dash-2 successor line. The addition of head end power capability during the Tri-Rail modification period required further electrical system changes to allow the locomotives to supply power directly to passenger car lighting, heating, and air conditioning systems, a function not originally part of their freight-oriented design.

Models by: Athearn