Passenger Side Mirror

Hello - it has been a long time since I have been to FABO (recent bout of insanity and worked on a 67 Mustang...).

So it is back to the 72 Dart.

I am getting it ready for the body and paint shop and want to add a right side mirror. I have a set off another Dart that are pretty good and will work. I am a bit confused however and the remote (left side) mirror has a stamped steel bracket that seems to mount inside the door. It has a small threaded hole for the phillips head screw and a larger hole for the stud/nut as well as the rubber seal that goes between the mirror and the door (outside). The right side mirror has a tapped screw and a stud, but no inside mounting plate - I have either lost it or never had it. The doors these came off of a long gone.

Does anybody know anything about this inside the door mounting plate for Dodge Darts (70 to 72)? The one on the remote mirror seems to be already threaded through the cables... another mystery.

Also, anybody out there have a template or the measurements for mounting the right side mirror. The fewer holes I drill the better.

Any help would be appreciated.