So I have a near mint 1997 GMC Sierra. A friend of mine hit the far right side plastic air vent with his knee and broke the air flow tab off. I found a good condition one and what to remove the old broken one and install this new one. This happened years ago and I changed it out but cant remember how I did it. All I remember was I did not have to take the dash apart or anything like this. Any ideas how to do this with out cracking the dash or plastic parts? I think these little teeth hold it in place? Here are a few pictures and the truck itself:



