I use a 5v fan over the end bell. I used an assoc. front body post and mounted it on the chassis near the endbell. I had to drill and countersink the flat head screw for the post. I then took the diameter down so it would fit the mounting holes on the fan.
I use hitec dcx 3 channel receivers so I plug my personal transponder into the third channel and the fan into the battery slot and let the rec. power the fan.
I will post pictures tomorrow.