My thought the same..Gonna try some clear silicone on both mirrors. Thanks for the reply..On my older JL, I had a rattle coming from the front also. Checked everywhere, but found it was coming from the passenger mirror. Sounds weird, but squeeze the mirror together with the window down. It might be your culprit. The mirror is pieced together with a plastic cap facing the wind as you drive. I resolved the mirror rattle by prying it apart and applying light seam of Gorilla glue. I know, it sounds cheesy, but it worked.