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Locomotive Phases - GE B32-8, B39-8, Dash 8-40B

The first Dash-8 units were introduced by GE in 1984 and were produced alongside the last Dash-7 units. Eighteen initial demonstrators were produced: Three B32-8's for BN, three B39-8's for ATSF, ten C32-8's for CR and two C39-8's for NS. Dozens of additional C39-8's were built during the next two years for CR and NS, but no more B32-8's, B39-8's or C32-8's were built before GE introduced a much-improved "enhanced" version of the Dash-8 series in 1987, which accounted for the vast majority of Dash-8 production.

Early (pre-1987) Dash-8 units carried over some spotting features of the Dash-7 series, such as the general style of the hood doors and a break in the hood width near the radiators, along with a second break in the hood width on the fireman's side closer to the front of the hood. The cab roof was still rounded and was the same height as on Dash-7 units (105" above the walkway), but the eaves were higher than on Dash-7 units and the walkway height on the 4-axle units was increased from a nominal 68.625" to 70". The hood behind the cab created a "hump" that was taller than the cab itself, and the radiator intakes were vertical and located under angular radiator "wings". The raised hood section behind the cab contained a boxy housing for the dynamic brakes, which had been incorporated into some B30-7A and C36-7 units a few years earlier.

The B32-8 was 2' 9" shorter than the B39-8 and Dash 8-40B, with length removed in the fuel tank and the center section of the hood. Continuing the trend of earlier GE units, the B32-8 had 6 engine room doors per side (indicative of the 12-cylinder engine) while the B39-8 and Dash 8-40B had 8 doors per side.


All 4-axle Dash-8 units used the same main frame thickness giving a walkway height of about 70". However, several combinations of overall length and truck centers were used.

Model Overall Length Truck Centers Notes
B32-8, Dash 8-32B 63' 7" 36' 7" Trucks 14' and 13' from front & rear pulling faces respectively
B39-8 (demo and early "enhanced") 66' 4" 39' 4"
B39-8 (late "enhanced"), Dash 8-40B 40' 1.5" Front truck forward by 10.5"
Dash 8-32BWH, Dash 8-40BW 39' 7.875" Rear truck forward by 5.625"

Detail variations - Early B32-8 and B39-8

The early B32-8 and B39-8 shared the same general spotting features as the Phase 1a C39-8, except for the dynamic brake housing on the B39-8, which was typical of Phase 1b and later units. These details are described in the GE C32-8 and C39-8 phases.

Transition: Early to "Enhanced"

GE made a large number of electrical and mechanical improvements after the first Dash-8 units were produced, which appeared in all production versions of the B32-8 and B39-8 introduced in 1987. Although these units sometimes have an "E" added at the end of the model name (as in B39-8E) the builder's plate apparently lacked such a designation.

Externally, the improvements made to later Dash-8 units resulted in an almost entirely redesigned carbody, which included the following changes:

Detail variations - "Enhanced" B39-8

Production B39-8's built for LMX and SP all used the "enhanced" design.

LMX B39-8

The LMX units, numbered 8500-8599 (plus two wreck replacements) underwent several detail variations over their production run, with the last group bearing the closest resemblance to the subsequent Dash 8-40B. These detail differences are based on my own observations.

LMX numbers8500-85218522-85408541-85498550-856585668567-8599
Rear headlight and grabironsRear headlight about 3/4 up the hood end, grabirons attached to vertical stripsRear headlight near the top of the hood end, grabirons attached directly to the hood
Truck castingsAdirondack, RockwellMostly Rockwell
Truck centers39' 4"40' 1.5"
Corner handrail notchVertical notch with bevel under handrail attachmentStraight vertical notch with no bevel
Fuel tankRoughly centered between trucksMoved forward by about 7"Some moved rearward by about 2.5"All moved rearward by 2.5"
Dynamic brake ventsEarly (as on Dash-7 and early Dash-8 units)Slightly taller, with square bevel inside top edge (as on later Dash-8 units) - also used on LMX 8554

Early LMX units used a mix of Adirondack and Rockwell truck castings. Adirondack castings had two small-ish holes in the middle of the sideframe and a smaller one on the right; Rockwell castings had larger holes in the middle of the sideframe and added a third large hole under the small one on the right. Almost all units numbered above 8540 or so used Rockwell castings. Truck swaps over the years led to some units having one of each.

LMX 8503 and 8540 were wrecked relatively early in their careers, and were replaced by 8503:2 and 8540:2. Both of these later-production units shared the appearance of the last batch of LMX units. However, LMX 8540:1 was also rebuilt and became GECX 8001, in the process combining the original (early) truck centers and fuel tank location with the later dynamic brake vents.

SP B39-8

The SP order of B39-8's (SP 8000-8039) had 40' 1.5" truck centers and early dynamic brake vents (as on LMX 8541-8566) and used a longer fuel tank.

Detail variations - Dash 8-32B, Dash 8-40B

As part of GE marketing, locomotive model names were changed around late 1987 to have "Dash 8" spelled out. This coincided with an increase from 3900 to 4000 horsepower for the 16-cylinder versions, so there was therefore no such thing as a "Dash 8-39B". Cosmetically and mechanically, the 4000-horsepower units were an incremental evolution from the last 3900-horsepower units, with the late B39-8 and Dash 8-40B being virtually identical. Compared to the last version of the B39-8, the Dash 8-40B had the following changes:

Dash 8-32B

All production B32-8's were built for NS in 1989—after this nomenclature marketing change—and they were therefore labelled by GE as "Dash 8-32B". For their purposes, NS shortened the name to "D8-32B". Aside from the 2' 9" shorter length (and two fewer hood doors per side) they shared almost all the same spotting features as Dash 8-40B units. However, the front truck remained 14' from the front coupler pulling face, as on early Dash-8 units.

Dash 8-40BW, Dash 8-32BWH

Two variations were built with a wide-nosed cab: The Dash 8-32BWH (for Amtrak) and the Dash 8-40BW (for ATSF). Both units maintained the overall length of the Dash 8-40B (66' 4"), but the fuel tank was positioned near the rear truck, with both air reservoirs in front of it (rather than one at each end). Additionally, despite some sources that claim otherwise, both models had the rear truck moved forward by 5.625" from the Dash 8-40B, shortening the truck centers from 40' 1.5" to 39' 7.875". Both changes were presumably to offset the added weight of the cab.

As on the Dash 8-40CW, the walkway side frame was narrowed, leaving more of the underframe exposed. The wide-nosed cab was about 5" taller than the standard cab, but unlike on the Dash 8-40CW, the frame thickness and the hood behind the cab were not modified to account for the extra cab height, as the frame height on the Dash 8-40B (about 70") was already low enough to accommodate the taller cab. With the rest of the hood largely unmodified from the standard-cab version, the Dash 8-40BW had a distinctive jump in height from the hood to the cab roof.

While the cab was largely the same externally as the one on the Dash 8-40CW, it was not identical. On the Dash 8-40B and Dash 8-32BWH, the front of the short hood was slightly more pointed in order to clear the step wells, resulting in shorter sides and more steeply sloped front corners.

As on the Dash 8-32B, the Dash 8-32BWH had a shorter engine room compartment than the Dash 8-40BW, with six tall engine room doors per side instead of eight. However, as the frame was still the same length, the extra length was added to the hood section behind the cab.


Conrail. (1989). Locomotive Diagrams. Retrieved February 2013 from http://rr-fallenflags.org/cr/cr-lb89.html

General Electric. (1984). Series-8 Handbook. Retrieved September 2012 from http://rr-fallenflags.org/manual/d8-hdbk.pdf

General Electric. (1987). Operating Manual, 1987 Series-8 Diesel-Electric Locomotive. Retrieved January 2015 from http://www.rr-fallenflags.org/manual/D8-OM.pdf

Strack, D. (1997). Union Pacific GE Dash 8 Locomotives. Retrieved December 2014 from http://utahrails.net/articles/up-dash8.php.

The Diesel Shop. (2011). General Electric Four-Axle Dash-8s. Retrieved January 2015 from http://www.thedieselshop.us/GE_Dash8B.HTML.

 Copyright © Michael Eby - Page code last updated 2017-02-08