The Stovebolt Site Forums The Shop Area Interiors interior mirror, 1953

The one in my 50 is threaded.

I don’t have a good pic but you can look at this one.
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You can use the zoom feature in Picasa to get up close.
It’s the magnifying glass icon with the plus on it.
If I remember right the division bar is threaded, and the center windshield trim piece is a drilled thru hole.

There is a larger clip on mirror on it.
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Good Luck