Back in the 50's some outside mirrors were options especially on the passenger side door. I bought my 57 Bel Air from a fella out of Califonia and the mirrors were already in place so when I restored the car I put them back in the original holes. Here are some pixs my 57 and where the mirrors are located. Hope these photos help you out. Should you find that these mirrors are in the correct factory position make sure that they clear the wing windows when opened.

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