Before you go getting all crazy like see if you can fit the assy. in the door?
I went thru a whole big deal on the vent window frames on my 81.
The ones from the truck were rusted & broken and I got a good set years ago from some place, member?
I could not fit them in the doors and when I matched them to the old they were different.
I had to get a 3rd set that were a little different than the first set but they would fit into the doors.
I am sure that bracket I had to cut off just to get them in the doors.
I think I did a thread on the different vent window frames and maybe the years they were from when trying to get mine in the doors? Anyone remember this thread? Pictures were from 10/13-15/2019
I just went thru my pictures and I don't see that bracket on any of mine.
Also IIRC when trying to fit it in the door I could not see where that bracket would tie in as I don't think it hit where the mirror screws were.
Dave ----