I have a cap in the 76 I am well pleased with. Yes it came with a tube of silicone to help hold it in place. The instructions say you don't have to remove the dash but... I don't want to have to fiddle with the darn thing if I ever needed to remove the dash, which I ended up doing this year, so I took the dash out and used a heat gun to help contour the defroster vents so that I could line the holes for the screws that go into the firewall and hold the dash front in place.
I have a half cap for the 80 project I wasn't all that happy with the way the cap for the 5th gens looked when I got it but now... they make a full cap so I'll probably correct that before I put the interior back in it. The full caps you really can't tell, in my opinion, that it is a cap, I've seen one or two installed. One was a really good job and the other was not bad but not as good as the first one. So I guess it depends on your creativity or patients or skill or something like that.
Then again they could have been from two different vendors also.
Sounds like a crap shoot. Wish I could afford a new one. My son got
one on EBAY ($161) but the rat backed out of the deal. Anyway my
son and I are pretty good at getting things to fit and at this point there
is no turning back. I will take some photos of the finished job.
Thanks for the help guys. I really like this site.