[Killer Bee]

the OE are machine thread and the one aftermarket set I tried was screw thread..

all three screws thread into a single plate, screw tails would be tough to bite in the narrow access of the door shell..

and once the threads tails are boogered up, they're going to be even more difficult to back out of the nut plate..

the recessed heads in the mirror base makes this more challenging, however attacking the fastener there would still be my preference..

the fastest solution with the least moves, highest probability of success, and least amount of collateral damage = cut a socket to fit..

if it was installed with a socket, it can be removed with a socket.. just don't forget to spray the the threads inside the door..

have to remove the door panel and trim to access door shell openings to retrieve nut plate and position new one either way..

good luck!