Hey guy's, I bought an SD40-2 off Ebay for my birthday a few weeks ago almost brand new. The heading said it was water cooled and forced air. These unit's must be custom built because they are Athearn blue box locomotives. I'm waiting on our next show so I can run it and see what it's about. From what I was told, these components where installed to reduce heat and expand the life of the motor but there are only meant for running 8-10+ hours. It has a water tube that is sealed and it circulates water through it. On the rear of the locomotive on the top of the gear box housing on top of the rear truck it has a miniature fan that draw's air up from underneath the locomotive and forces it to the front and out of the bottom of the front truck. Pretty darn neat if I say so myself. The cooling system is wired directly to the trucks and not to the motor so it's not drawing more amps, therefore it can be run with the typical Athearn locomotive. It came from a guy in Ft. Worth, Texas. Does any one else here own any of these special built units?