CSX's 4400-hp DC-traction GEs are often called C44-9Ws by railfans, and I believe even by CSX itself. However, I can certainly see that they are not, having Dash-8 trucks. According to http://www.thedieselshop.us/GE_Dash8C.HTML they are C44-8Ws, a model only CSX has. http://www.thedieselshop.us/GE_Dash9.HTML confirms that CSX has no C44-9Ws. My question: What are the external differences between the C44-8W and the much more common C40-8W?
The primary difference between CSX's C44-8W and C40-8W is the radiator grills or "wings." If you compare the two, you'll see that the "wings" on the C44-8W are thicker, like a true C44-9W owned by UP, BNSF, etc. GE built CSX's units as an early "experiment" or transition unit to the Dash 9 series, and they needed to beef up the radiators to cool the higher horsepower prime mover. I have a feeling there are probably some other minor differences, like maybe the placement of a couple hatches or panels, or something small like that, because there were lots of variations like that just within the Dash 8 and Dash 9 series themselves. I haven't really put photos side by side to look at the two, but hopefully someone else can fill us in. Hope that helps!
The Trains' Field Guide to Modern Diesel Locomotives says the CSX C44-8Ws have the split cooling sytem of future -9s, and the rooftop dynamic brake intake was relocated.
GE had already moved the dynamic intakes to the sides from the roof by the time the C44-8s were built. This is a phase indicator, it was done at the time of the widecab introduction (1991) GE went to split-cooling not for horsepower, but for fuel economy (and to a lesser extent, emmissions, but this was mainly a by-product of better fuel economy). The C44-8Ws were the first production units to get split-cooling (though GE had tested it much earlier After the first three C44-8Ws were built in July 1993, split cooling became an option. All -8s built afterwards would have it, save for UPs C41-8Ws.
I think the early CSX units I photgraphed were actually labeled on the cab as CW44-8 and later all were changed to CW44-9. Harold