Here is my attempt at adding PF to the BNSF. I still need to make decals to cover the battery and IR receiver. I even have room inside between the battery and IR receiver for the polarity switch to run 2 motors on this one. I have several other modifications that are also going on with this one, but for just adding PF to this, very few additional parts are needed. I even have an on/off switch built into the rear fan blade like the one on the 7939 cargo train.
As you can see, I changed the roof of the cab (lowered its height slightly and got rid of black roof), I changed the rear panel, I am adding steps front and back, I tiled up the roof, and changed fan blades over to the train wheels that actually work well as fan blades. Still waiting on a few parts from BL, then its decal time.