i've got the viewer like the one from classic parts. it's plastic not like the original glass and has a stepped lens. it works great as i have a fulton visor on my 53 p/u. once you get it set up, just look at the viewer and the red/green light will light up in a v pattern, just wait for the color to change to green. i'm 6'3" and welcomed this inovation to my truck! it's a lot better than imitating a vulture at the traffic light
cheers