Based on the photo of the CSX car in your first link, the control valve is to the right of the air reservoir. I would reference the documents on the NYAB site for dimensions and details.
I'm not sure which cad program you are using, but in many programs you can attach or import the drawing, scale it to proper size, and use it as an underlay to trace or reference. There is also the possibility that you could extract a dwg file from the document pdf, but that only works if the drawings in the pdf are in vector format, and you would need a program like Adobe Illustrator to do the workflow. Even then, the entities are still only 2d. You still have to build the 3d model.
Hope that helps! I look forward to seeing what you come up with.
Jim
