Windshield mount? If so, Pete Debella has the best reproduction windshield mounted rear view mirror that I have found. It's a new product for Pete. Scroll down this page to nearly the bottom and you will see a 2A and 3A version (different bracket style) that has the original looking mirror head. They are pricey at $50.00 but I haven't found anyone else come close to matching the original accessory add-on from the 1940s and 1950s.
https://www.debellajeepparts.com/cjpremiers.htmI currently have the squared off version he offers (just down below the versions on this same page). They are decent, but if you want an original look, the $50.00 version is worth the price.
EDIT: Forgot to mention that the nicer version uses tinted glass. The square version does not. I get blinded by drivers behind me with the square version. I have to point it down when driving at night.