I parked in front of house (careful to miss the tree
this time) and assessed how to install the mirror.  It
was so easy.  No door panel to remove.  I only had to
pop off a plastic cover which reveals three studs with
nuts and washers.  I had my trusty Ace Hardware nut
driver set in the truck in an five minutes I had the
mirror assembly replaced.
That was smart.  A smart labor saving design on the
assembly line and a smart design for the repair shop
or home mechanic.
Of course mirror removal (manual mirrors that is) is
also easy on our old AMCs.  Just two phillips head
screws.