The sunvisors on my 57 Brougham are still in good shape. That car was imported in 1958 in Switzerland, and, as you know, we dont have here a climate like California, Arizona and so on. Furtehrmore, since I have that car (1984), it stored in a closed garage.
On the other side, on my 56 Biarritz, they were gone when I got that car in 1986! I could buy repro sunvisors, just tinted plastic with the original supports.
Roger