The rear doors are the same integrated speakers, but I believe they're 5.25 instead of 6.5.
As for hacking the existing speaker, cut the crappy speaker out, dremel the lip off the factory speaker and there you go. Speaker gasket material also helps. Took about 10 minutes with a couple of test fits. Cutting the lip off may not be needed as I did this to the rear doors. I got IA spacers for the front with the extended pins.