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Locomotive Descriptions and Phases - EMD GP40-2

The GP40-2 was introduced by EMD in 1972 as a replacement for the GP40. It retained the same 3,000 horsepower 645-series engine but received a host of mechanical and electrical upgrades geared at improving reliability and ease of maintenance, the most substantial of which was the introduction of modular electronic components (which had been tested on the DDA40X starting in 1969). Production continued until the end of 1986. The GP50, introduced in 1980, was built concurrently with late GP40-2 production, and both were succeeded by the GP60.

Like the GP40, the GP40-2 can be identified by having four axles, three 48" radiator cooling fans and a clean-lined hood with a single turbocharger exhaust stack (changed to a flat silencer housing on later units). The differences between the GP40 and GP40-2 are listed below; for the differences between the GP40-2 and GP50, see GP50 Phases.

Transition: From late GP40 to early GP40-2

While all the overall dimensions and proportions were retained with the start of the Dash-2 series, many small detail changes were made to the entire locomotive. As a result, almost every part of the cab and hood was changed in some way. The following external changes were made with the introduction of the GP40-2:

Cab and cab sub-base


Underframe and walkway


These drawings compare a late GP40 with an early GP40-2, both built to BO/CO specs.

Left side: GP40 -  GP40-2

Right side: GP40 -  GP40-2

Phases - GP40-2

The GP40-2 underwent a similar evolution to the GP38-2 and SD40-2. I initially based these phases on SD40-2 phases by Scott Chatfield, with details added based on my own observations. I later added Phase 1a2, 1b and 2a2 based on the GP40-2 roster compiled by Robert Sarberenyi. While phases often differed between EMD and GMD versions of the same model, in this case all GMD GP40-2(W) and GP40-2L(W) units had Phase 1a1 or 1a2 GP40-2 spotting features.

Numbers correspond to the illustrations shown below.

Phase 1a1 1a2 1b 2a1 2a2 2b1 2b2 2c1 2c2 2d 3
Dates 1972.01 -
1972.08 -
1976.04 -
1976.01 -
1978.04 -
1979.01 -
1979.05 -
1979.12 -
1980.09 -
1981.05 -
1983.03 -
Inertial air intakes 1   Ridge added along top Ridge added along bottom
Radiators, fans 2 Square wire grid intakes;
curved grabiron behind fans;
flat-top radiator fans
Corrugated intakes;
relocated lift ring and flag holder aft of intakes
Angled grabiron behind fans
(late Phase 2b1)
Q-type radiator fans
Underframe 3   Revised fuel tank vent pipe Revised air reservoir piping on conductor's side
(appeared on some late Phase 2a2 units)
Cab 4 Hinged sub-base doors;
riveted side panel
11 rivets along top/bottom
Sub-base doors with lift-off tabs;
riveted side panel
13 rivets along top/bottom
Welded side panel
Battery box covers Bolted, small louvres Larger louvres Horizontal rib added
(bolted version only)
Latched, lift-off tabs
Short hood 5 81" length 88" length; circular vent on right side Bolted hatch added on top
ECAFBElectrical cabinet air filter box, located on the left behind the cab
Separated from cab Flush with cab
Pilots, steps 7 Straight upper end plate corners;
straight coupler cut levers
Notched upper end plate corners;
raised coupler cut levers; revised upper pilot/drop step area;
front anticlimber/sill extension added; notched stairwell side sheet
End handrails 8 Flush with pilots;
inward-facing central handrail stanchion supports
Wrap around pilots slightly;
outward-facing central handrail stanchion supports
Dynamic brakes 9 Batten strip at rear of dynamic brake housing No batten strip Dynamic brake housing moved rearward
Exhaust 10 Raised exhaust stack Silencer with opening at rear Silencer with opening at front
Blower duct Flat, wide, two ribs Angled "laundry chute"
Frame side sill Narrow over air reservoirs, wide at ends Narrow over entire length
Phase 1a1 1a2 1b 2a1 2a2 2b1 2b2 2c1 2c2 2d 3

Other details


These two drawings illustrate typical early (Phase 1a2) and late (Phase 2d) GP40-2's built to similar Chessie System specs. A few details represent railroad-specific options, such as rock deflector pilots, a box behind the ECAFB, slotted battery box covers (on the Phase 2d version) and horn variations.

Phase 1a2 -  Phase 2d


Foster, Gerald. (1996). A Field Guide to Trains. New York, NY: Houghton Mifflin.

Sarberenyi, R. EMD's GP40-2 - Original Owners. Retrieved November 2014 from

Unofficial EMD Homepage. (2001). GP40-2 Order Numbers. Retrieved November 2014 from