Here's a picture of the mirror.
I agree that the heater was optional (listed that way in the 1966 Ford Truck Saleman's Data Book). As was the radio and Sun visors. I do not see the dash pad listed as optional. It is however listed under Standard features for all models as is windshield washers.
My apologies to MP as I did not intend to highjack his wanted Ad. I just wanted to help folks understand what mirror I believe he was after. This mirror can be hard to describe let alone find one.
-Terry