This was from a VW Porsche dealership. Looks like a early Carrera 911-731-017-20 mount but with a metal mirror back. I have no part numbers so it may be a aftermarket part but It is original equipment quality and weight.

It has never been installed as I have owned it since new but did not have the foresight to retain the package or numbers.

Do your research if you care about originality otherwise just use it as a cool part that no one can identify.

Possibly for 914 912 911 type 3 or ?...