Allow me to be the devil's advocate. I have a Fulton on my '38 and love it. It does in fact make the interior cooler in that it blocks some of the solar radiation from coming in the windshield. Some left hand traffic turn signals can be blocked so a viewer can help. I have one on my '38. The clam shell type of viewer mounts to a garnish molding screw so there's no need to drill holes to mount it. There will indeed be four small holes to be drilled in your door jamb for mounting the visor. Don't drill them into the drip rail as I've seen some done. I personally do not like the sleepy sombrero look that the stock mounting brackets provide so I made an extended center support bracket arm to get the front of the visor up. Be sure to mount it with about a two inch gap across the trailing edge to let air out.

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.