The following
phases were compiled from existing sources of GP7 and GP9 phases.
.
- GP7 Phases
-
Phase 1
(1949.10 - 1950.11)
-86" engine
room doors
-No box on
walkway behind left side cab
-Solid fuel
tank skirt
-Sloped pilot
plates
-36" dynamic
brake fan
-Full-height
hood straps before/after engine compartment
Phase 2
(1950.06 - 1953.03)
-Dynamic brakes
optional
-Box on walkway
behind left side cab
-Slotted fuel
tank skirt on units with 1200+ gallon fuel tank (after 1952.03)
-No sloped
pilot plates (after 1952.07)
-48" dynamic
brake fan (after 1952.08)
Phase 3
(1953.03 - 1953.12)
-82" engine
room doors
-Hood straps
either stop at top of engine room doors (dynamic brakes) or are absent
(no dynamic brakes)
Phase 4
(1954.04)
-GP9 Phase
1a carbody, GP7 internals
.
Phase 1a
-Fabricated
pipe handrail stanchions
-Deep fuel
tank skirt
-Four 36"
radiator fans
Phase 1b
-Stamped channel
handrail stanchions
Phase 2
-Lower louver
groups removed from generator room doors (behind cab)
-2 louver
groups added on 3rd engine room door
Phase 3a
-Fuel filler
moved forward
-Shallow fuel
tank skirt
Phase 3b
-Louver group
under walkway in front of cab replaced by 2 small louver sets
Phase 3c
-Two 48" radiator
fans
- Other details -
-Phase 3c may
be considered a subset of Phase 3b, since production overlapped.
-Fuel tank
skirts were often modified and are not a reliable spotting feature.
-GMD-built
units did not follow the same development of phase details.
.
Michael Eby 2008-2009