HO GP39-2u Locomotive, ATSF #3409

HO GP39-2u Locomotive, ATSF #3409 Overview

Starting in 1986, Santa Fe rebuilt 50 GP39-2's in their Cleburne, TX shops, designating them as “GP39-2u's”. The “u” stood for “upgrade” which was a common term for Santa Fe rebuilds during this time. Other than the mechanical and electrical upgrades, Santa Fe added some unique details that distinguish these from their non-rebuild counterparts. These changes include: Fuel tank moved to the rear, new “swing out” style number boards, new style exhaust stack, and added an equipment door to the right side hood, just behind the cab. They also featured “switcher” style walkway steps for crew comfort during switching moves. A few even received modified corrugated radiator grilles.

In the decade between 1974 and 1984, EMD produced the GP39-2 for seven North American railroads. The basic design followed most four axle road diesel switchers for the time. Borrowing improvements from the GP38-2 and GP40-2 designs, this mid-horsepower road switcher utilized a turbocharged 12-cylinder EMD 645E3 diesel engine for its prime mover. With 4 fewer cylinders, the smaller engine provided a distinctive long hood on the phase II and phase III bodies, where the clean room/engine compartment doors were set back from the cab further than predecessor locomotives.

Sensitivity to fuel economy in the 1970s justified the GP39-2 in the locomotive market. It also laid the ground work for EMD to start exploring locomotive designs that utilize engines with larger piston displacement yet possess fewer cylinders. This approach has become the foundation to modern locomotive technology.