you'll find better luck in the Grand Cherokee forums, this is the Cherokee forums. But since they are so alike you can fit 6.5's in the front doors by just drilling new mounting holes, and you can also fit 6.5's in the rear hatch, my speakers came with adapters to fit larger speakers in a smaller speakers mounting holes so i used those. Not sure if you can drill new mounting holes in the hatch since i havent personally done it and i didnt really inspected that area much when i was installing my speakers. Not sure about GC dash speakers since in the cherokee you have to rip out the whole dash to get to them (or so im told)
Here's my setup
Since then i have removed the adapters on the front two doors which made the speakers retreat about 1/4 of an inch, that might have given me enough room to where i didnt have to trim the pannels, not positive tho since the factory speakers grills arent there anymore for me to see if they touch the speakers or not lol.