I have a solution for repairing the rivnut that the side mirror mounts to as long as it’s salvageable. You will need some minor welding skills for this to work. I chased the threads on the stainless steel mounting screws and the rivnut that is mounted on the door where the side mirror is located. The Rivnut still had integrity, so instead of replacing it, i spot welded the rivnut in a few spots on the top where the collar is visible. Sanded the spot welds so they looked clean and attached the mirror. Below is a video showing the process. Hope you enjoy and get something out of it.