I purchased new defroster vents for my 64 Barracuda. Pulled the driver's bucket seat out to make it easier (I'm 72) to get under the dashboard. Still couldn't reach up there with a socket and extension to get at the 3 thread cutting nuts. Do i have to remove the instrument cluster to get at the nuts?
It would probably be easier in the long run, especially when installing the new ones and trying to get those nuts started again- not the easiest thing to do with three extensions and two universal joints on a ratchet!
On the passenger side, remove the glove box liner- it's still not easy, but it's easier. Hopefully you can get them without removing the heater controls- the cables tend to get in the way a bit...