See my second photo here:
Trips & Airports - San Francisco to Toronto, C 182RG
I'll be flying the plane again in a couple of weeks, and will review the logs to see if I can determine where it came from. In the mean time, you can search the mirrors used on Cessna amphibious floatplanes, it'll be the same thing. It is better mounted further outboard that the strut for a better angle of view.
They've ordered mirrors for the 182 amphib I'll be flight testing in two weeks, I'll know then where they come from, if I've not been back to the 182RG yet...