Measurement for JBL
I did my best to measure the opening for the JBL and came up with the following dimensions: 8 7/8" wide at bottom, 8 9/16" at the top, with a 1/4 inch rounding at the top, by 4 1/8' high. It should be like davisc23 said in that it's the same opening as the non-jbl systems w/o the recess. Someone might want to concur as it isn't a perfect rectangle.
BTW, I found a shop in the DC area that sells the AVN5435 for $1700, they don't have it in the shop so they would have to order one. I'm going to stop by the store on Saturday so I can get their opinion on the installation. I'm kind of skeptical using a random dealer to do the install, so I might have Tweeter do the installation.