Removed the OE mirrors today. I learned why the mirrors weren’t getting blown around as badly as they might have been. Someone drilled through the lower door mount and through the main mirror tube and installed a self tapping screw to hold the mirrors in position. The hole in the mirror tube has worn over the years allowing about 5 or 10 degrees of motion. The main mirror tube has a clamp behind the main lower mount to hold it firm. On mine, both sides, two of the clamp screws were not in place at all.