I thought I'd add some clarification on the variations and model designations:
--CN 9400-9530 and 9531-9632 are GP40-2L(W)'s, with builder's plates indicating GP40-2L. The two series are nearly identical save for the length of the cabinet on the left walkway behind the cab.
--CN 9633-9667 and GO Transit units (later CN 9668-9677) are GP40-2(W)'s, with builder's plates indicating GP40-2. CN and GOT units have different fuel tank sizes, but both are smaller than on the GP40-2L(W).
The "L" stands for Lightweight frame. To maintain adequate strength, the frame on the GP40-2L(W) is several inches taller than on the GP40-2(W)--so the walkways are actually higher than on some SD-series units. The GP40-2(W) frame is the same as that on any other GP40-2. The easiest way to tell the difference is by looking at the height of the jacking pads and the gap between the air reservoir and fuel tank.
http://www.railpictures.net/viewphoto.php?id=55655Aside from the cab, the steps/pilots, fuel tank, rear hood doors/handbrake, blower duct and rear headlight (among other small details) are different from a standard GP40-2. Snow shields, rear-mounted horn and lowered fans are CN modifications that were not present when built.
