This post could also have gone under body.
Doing the tail panel of the 71, and putting the tail lights together, i noticed that the factory reflector paint inside the bezels was not very good. So i sanded inside the concave areas with wet and dry and then polished with metal polish to give a mirror finish. The difference in brightness of the lenses is amazing. I am a bit worried though that with time, the brightness will dull off. The sure fix is getting some tin foil and carefully cutting to shape and gluing in, shiny side out. Works almost as well. (I did this method with the front indicators -they are bright now!)