[FirstOwner69]

Pete is correct that the mirrors are just screwed to the doors using hex head sheet metal screws. An early encounter with a parking meter convinced me that this is not the best fastening system. This is one of the not too obvious places where I varied from original on my truck. When I removed a mirror from a late 70s van, I found that GM had refined the fastening system to what is pictured below. They won't rust because they are stainless, won't tear out of the door and are cushioned so the mounting bracket won't damage the paint. The casual observer will never notice. You can see them in use in the 2nd and 3rd pictures in post 19.

https://www.ebay.com/itm/1-4-20-Jack...cAAOSwwfFeJeie