When I purchased my Tang Band 6.5 subs, I found a review on parts-express from a dude that installed them in the back doors of a CC. I'm not sure if he had to make a spacer ring or not. I installed mine in the front doors where the factory 6x9s were and there was plenty of depth. Those little subs have a depth of 4.33 inches BTW. I didn't deaden the door though and it vibrated and buzzed the door panel like crazy. LOL. I was meaning to install them in the back doors of a KC but there is a structural rib right behind where the speaker mounts that prevented installing them there. Just about any component 6.5 set will fit fine in there I'm sure.