I took a shot at purchasing the Metra 6x9 Speaker Adapters (82-3005) for my 2010 Chevy Camaro even though the adapters are specifically for newer model Chevy/GMC trucks (according to the item description and Metra Tech Support). I needed to fit a set of Focal K2 Power 6.5" Component Speakers on the rear deck of my Camaro and when I saw that the Metra Speaker adapters had the same mounting tabs I went ahead and bought it from Sonic. I had already fabricated a 6x9 mount previously when I changed out the Boston Acoustic speakers for a pair of JL Audio 6x9's so when I tried the Metra 82-3005, it was almost a perfect fit. I had to make a few minor modifications but not on the adapters themselves, although the adapters are a bit too high. I would still recommend these Metra Speaker Adapters for fellow Late Gen Camaro owners who need to fit component speakers on the rear deck lid of their Camaro's, but only if they are capable of doing it themselves.
Because I don't think installers would do it, and if they do, they would charge a lot and probably do it wrong.