My brother has a notchback mustang, so his rear speakers are mounted in the rear deck. The factory speakers back there are 5x7. Many people make 6x9s work, but there is some modification involved.
With that in mind, we went shopping for some speakers. We found a great deal on a set of 6x9 speakers that sounded the best to my brother and were in his price range. The problem is, the cones on this particular speaker stick out quite a bit from the top edge of the speaker.
We're trying to mount these without having to cut his deck to pieces. The only feasable way I can see mounting these, I've illustrated below.
Basically we use the giant ****ing cone pressed up against the deck to hold it sturdy, and then just drill the holes and tighten it down with some nuts and bolts. The plastic on the cone is sturdy enough to hold, but we aren't sure about space around the edge of the speaker, as well as how everything will sound with it pushed right up against the deck the way it is.
The other idea would be to just get some blocks of wood and use them as spacers.. I guess thats probably a better idea now that I think about it..