'72 Dart, 27k original miles

I don't think you have to remove the dash to change the vents if they will clear the windshield coming up . I've never tired.
But you would have to take some things out of the dash to get your arms up in there to remove the nuts on the plastic studs.
It would be a PITA for sure, but with that nice interior I can appreciate wanting to sweat the details and have it perfect.