Locomotives Phases - EMD GP38, GP39, GP40

Phases

These phases are based on the GP38, GP39 and GP40 rosters compiled by David Thompson.  I have modified some of the phase descriptions after discovering some inconsistencies in the end plate design, which varies depending on step height and is therefore not always a reliable spotting feature.

Phase 1a1: 1965.11 - 1966.03

• Cab sub-base doors: Smooth
• MU receptacle housing: short, wide, angled side
• End plate: Version 1 (small tabs at bottom steps)
• Steps: short
• Footboards: Version 1 (flat plate on side extending behind end plate)
• Fans: Flat center cap
• ECAFB: No
• Electrical cabinet air filter box, located on the left behind the cab
• Short hood grabirons: Top-mounted, straight
• Radiator intake subscreen: Diamond mesh
• Blower duct: Flat
• Located on the left hood behind the cab
  
• Front taper on dynamic brake housing: Short, angled
  
• Handrail stanchions: Uneven spacing (closer at rear), bottoms not lined up

Phase 1a2: 1966.03

• Left cab sub-base door: rib along bottom

Phase 1a3: 1966.04 - 1967.09

• Both cab sub-base doors: rib along bottom

Phase 1a4: 1967.06 - 1967.07

• Fans: open-top (GP38)
  

Phase 2a1: 1967.07 - 1967.10

• MU receptacle housing: tall, narrow, angled bottom
• Appeared on some late Phase 1b units
  
• End plate: Version 2 (angled sides at bottom steps)
• Steps: tall
  
• Some later units retained shorter steps.  These units retained the end plate appearance of Phase 1 units.
• Footboards: Version 2 (beveled plate on side flush with end plate)
  
• Units with high-clearance steps retain older-style end plates but use later-style footboards.
• Fans: open-top (GP40, late Phase 2a1)

Phase 2a2: 1967.09 - 1968.02

• ECAFB added

Phase 2a3: 1968.02 - 1968.06

• Short hood grabirons: Bottom-mounted, U-shaped

Phase 2b: 1968.06 - 1971.04

• Radiator intake subscreen: Square wire grid

Phase 2c: 1971.04 - 1971.12

• Blower duct: Ribbed
• Front taper on dynamic brake housing: Long, nearly straight
• Handrail stanchions: Even 48" spacing, bottoms lined up

Phase 3: 1971.12

• End plate: Version 3 (Straight edges, no extension at bottom steps)
• End plate used on later Dash-2 units
  

Model variations

• Due to small production numbers, all GP39's are Phase 2b.

Other details

• Standard fan arrangement used tall radiator fans and a lower dynamic brake fan.  Some units had lowered radiator fans, or dynamic brake fan raised on a rim.
• Multiple fuel tank sizes available: 1700, 2600, 3000, 3200 and 3600-gallon capacities.
• Sanding nozzle routing varied, either under or through brake beams.
• ECAFB was retrofitted to many earlier units.

Transition: From Phase 3 to subsequent Dash-2 series

Despite a similar appearance, the GP38/GP40 shares hardly a single body panel with the GP38-2/GP40-2.

Cab and cab sub-base

• Battery box covers bolted rather than hinged
• Left-side battery box cover lengthened rearward
• Bolted, rectangular cab side panel around side windows
  
• Rear cab roof overhang
• Larger electrical cabinet air filter box
• Larger handbrake notch in nose
  

Hood

• Modified central air intake and blower duct
• Shorter dustbin hatch
• On the roof behind the cab
• Oblong water-level sight glass
  
• Right rear of the hood
• Rear hood doors grouped 2-2-2-1 instead of 1-2-4
• Circular access hatches at top corners of the long hood end

Underframe and walkway

• Optional M-type Blomberg trucks
• Air reservoirs moved rearward
• Lengthened walkway blower duct
• Handrail stanchions reverted to uneven spacing
• Similar to early GP40; closer-spaced at rear