I put a dash cover on mine, and for the price I am very happy. To install mine I took the entire dash out to thoroughly clean the dash frame and to paint the metal parts of the dash below the cap. Recognize that I did not have a windshield at this point, so taking it out was easy. Also, I was installing Vintage Air Aircondtioning and having the dash out made this a lot easier especially with their connectors onto the stock factory air dash vents. My 74 Chally had factory air, and the new cap fit everything fairly well. a couple of issues but not bad.
A couple of points.
1) I wish I found one for air conditioning that had NO speaker outlets. I put in two large speakers on the package shelf, and wish I didn't have to have a fake speaker cover in the middle. Not to mention that new speaker covers run $65. What a rip off!!
2) Make sure that you fill in any cracks, tears etc, in the old dash cap, as if you don't they will cause problems.
3) My instructions said to "test fit" the cover before putting on the adhesive, then if all is good take it back off, and put on adhesive.
DONT DO IT...
That cover fits on tight enough that you kinda have to force it over the peak. Mine fit well... But then I wasn't able to get it back off so that i could apply the adhesive, without it appearing that it would tear !! I ended up being forced to "lift/pry" it up and then shooting 3M spray adhesive using a tip under it and working around doing this. Also, since i dont have a speaker in the large middle speaker hole, I used that area to "bolt" the cap into there. Luckily it is holding tight!! If I hadn't taken the dash out of the car, I think I would have been screwed, and not able to get the adhesive into place.