[sick472]

I don't paint the transmissions. There's not any advantage unless it just for personal preference and the desire to color coordinate. Some of the exterior parts are regular steel and I paint those, but the aluminum, I just clean it and sand it to my taste.

Transmissions don't get that hot, but engine enamel is an excellent paint for transmissions. It will cost a few more dollars than non-high temp paint, but your only talking a can or two to do the whole transmission. Make sure you don't sand it too fine. Aluminum can shed paint easier than steel and should have some rough surface for the paint to adhere to. If your going for real smooth on the aluminum, look for a self etching primer first, then a light sanding, then the paint.