I used a mix of parts from GMM louvers to BLMA grab irons and on and on. The long hood is an Atlas GP7. The cab, short hood, frame, fuel tank, cut levers and handrails all came with the kit. The plow is a Sunrise debris kicker and the AWW is a Loco-Detail piece (good luck finding another one of those). The cab light housing came off an Atlas GP38. It was closer to the TCWR version than either housing included in the kit.
The exhaust hatches were from Shapeways, the antenna stand is Kato and the Sinclair is a Sandro S. piece.
The decals are Micro-Scale. I masked and painted all the striping as the MS striping decals weren't right for this engine. The couplers are Micro Trains 1015s.
All in all I'm happy with how it turned out. I was hoping to build a TCWR GP20C to go with it, but I'm not happy with the available engines to start from. I'll search on.