I have been away from the hobby for a few years and am wondering if a model of the GE C39-8 has ever been commercially available. The ones I served on during my railroad career with NS had a “shrugging its’ shoulders” appearance caused by the difference in height of the dynamic brake housing and the cab roof. You could spot a C39-8 at a considerable distance due to this feature. I think GE offered a C32-8 that looked very similar but we didn’t have any of these on the division I was assigned to.
In HO scale, just brass. RPP offered a C32-8 shell, which you could bash with the forth coming Atlas C40-8 or Spectrum C40-8.
http://www.bachmanntrains.com/home-usa/catalog/?function=detail&id=286
http://www.atlasrr.com/
click on Products on the left, New HO Products, then scroll down to Sept 30, 2003