It shouldn't make any difference. Whatever fits best. If it's the tag light side it would probably light your license tag up better if the tail light bulb is closest to the window but it'll light up either way. Don't forget the gloss white paint. It makes a big difference. Also a plastic lens passes more light than a glass lens.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.