The GE C40-8 model and its variants, the C40-8W (which simply meant it included the wide, safety cab), C40-8M (built for Canadian National, Quebec North Shore & Labrador, and BC Rail), and C44-8W/C41-8W (higher horsepower models that were built for three different lines) began the company's present-day reign as the premier diesel locomotive builder. By the time General Electric had finished building the C40-8 nearly 1,500 units had been sold through the mid-1990s. This success continued through the rest of the 1990s with its upgraded "Dash 9" models, which sold even better at more than 3,500 units. Today, you can still find the C40-8, and its several variants listed above, operating on CSX, Union Pacific, Canadian National, and BNSF (the only two Class Is not to purchase the model included the KCS and Canadian Pacific).
However, having now operated for three decades, and with many new models released since that time, most "Dash 8's) have been displaced, sold, or rebuilt; CSX, Norfolk Southern, Canadian National, and others have purged a great number from their rosters. They can still be found, however, on short lines and in lease fleets.
The GE C40-8 began production in November, 1987 as the more powerful
successor to the earlier C39-8. This new model would also firmly plant
GE as the present-day premier locomotive builder as it provided
railroads with the high horsepower and reliability they were seeking
with the resurgence of the rail industry occurring at that time (and
which continued through the 1990s). The GE C40-8 featured the builder's four-cycle model 16FDL prime mover,
which could produce 4,000 horsepower with a continuous tractive effort
of 92,750 pounds at 25% adhesion (using GE's ever-reliable 752 traction motor).
This was the same rating as the C39-8 although the C40-8 offered
better starting effort, 106,790 pounds. The model was also one of the
first to be equipped with the new high-adhesion (or HT-C) truck, which
helped to improve wheel-to-rail contact.
Orders for the new GE C40-8 took off quickly in late 1987 with five Class Is ordering the standard design including the Chicago & North Western, UP, CSX, Conrail, and NS (additionally, foreign line E.F. Carajas of Brazil bought four). Interesting, NS was adamant at the time about purchasing locomotives with the standard cab design and did not purchase wide, safety cabs until they were mandated to do so by the FRA. Through 1992 GE sold some 585 C40-8s. However, in 1990 General Electric unveiled a variant of the C40-8, the C40-8W, which featured the wide, safety cab. The carbody and exterior of this model has remained relatively the same with newer "Dash 9s" and through the Evolution Series featuring a sloped and beveled front nose, rectangular and thin windshields, the slight bulge behind the cab which housed the dynamic brakes, and finally the rear flared radiator "wing." When production had ended on the GE C40-8W in late 1994 it had sold nearly twice as well as its predecessor with some 900 units built.
It should also be noted that there were several variants of the model built aside from the popular C40-8W. The first was the C40-8M, which was identical to the original mechanically save for its full width cowl cab and carbody. Only used in Canada it was sold to BC Rail (which purchased 26), CN (who bought 55), and the Quebec North Shore & Labrador Railway (who ordered 4). Additionally, there was the C41-8W design. Again, identical to the original model save for its extra 100+ horsepower, the locomotive was bought only by the Santa Fe (25) and UP (83). Finally, there was the C44-8W. This design would become extremely popular in the "Dash 9" series but here it was ordered only by CSX, which purchased 53 (again, the locomotive was identical, mechanically, except for the added horsepower). While General Electric's locomotives are known for their reliability they have not tended to hold over the long run as EMD's designs such as the SD40-2. Still, given the relative young age of the C40-8 series most remain in service with the railroads (or their predecessors) that originally purchased them.
For more reading about General Electric diesel locomotives there are a few books written by noted historian Brian Solomon worth mentioning which highlight the history and background of the company. First, is GE Locomotives, a title that provides a thorough history of its locomotive line from the earliest days of building electrics and experimental diesels to the latest models built through the early 2000s. Second, is GE And EMD Locomotives: The Illustrated History, which generally highlights the history of both company's designs. As with virtually all of Mr. Solomon's you can expect well-written titles with large, crisp, and sharp photographs featured throughout.