I just figured out that my driver's side mirror is most likely from a '75 (it's larger than the stock size factory installed on '72 Corvettes). ISO an NOS or OEM 1972 driver's side mirror and stem (if glass is date coded, looking for a code corresponding to sometime between 09/71 - 12/71). The rubber base washer/fitting isn't essential.
ISO?
Are they the smaller ones? If so, pretty sure I have one, off my '73. Replaced it with a larger, safer one.
Steve