.....how do I tell if it is a “cheap” Fulton visor?
I don't believe there is such a thing as a "cheap" Fulton. There may be a poorly made reproduction.
That is the site I have bookmarked for reference. The only difference I've seen between the types of Fulton that would make a difference in whether it fits a particular type of vehicle is the side brackets (dogbones) and whether it connects to the windshield center strip. The Fultons I've seen are all adjustable for width to fit multiple applications. The Fulton on my '38 has dogbones for a different body style that we "messaged" a bit to fit my car. If you look closely at the link above in your quote you'll see two types of end brackets. One with the upper support leg toward the end of the bracket and one with it about half way down. My body style needs the one with the leg half way down but the Fulton I bought had the others. We made them work fairly easily. The second part is whether or not it attaches to the center windshield support. If you have a one piece windshield and buy a Fulton that needs to attach to the center support for strength you're going to have issues.
If you buy a Fulton that is complete (I've seen a number of them with broken mounting tabs on the dogbone legs) and pay attention to whether or not it mounts to a center windshield support you should have no problems mounting it.
