The front drivers side is like a 2.5"x3.5" - there's no direct replacement availible. The passenger side front is like a 3"x4.5" or some stupid thing - nothing for that either. Also - you can't use the factory wireing because it's common ground, so you'll have to rewire anyway. Might as well replace those crappy speaks with something else while your at it. I got some speakers that were close in size, and just MADE them fit - lots of work with a dremel - they are in, but it was a pain in the rump roast (talking about my Brat here). On my wagon, I just disconnected them, and put the tweeters on the A pillar, and the mids in the forward section of the door.
Problem with the door speakers is they are really shallow, and anything you get that will fit in there is going to be deeper, so you'll have to space them out. The factory location is REALLY bad as it projects the sound right into the seats :-\ I built custom boxes and mounted them further forward after removing the map pockets.
It's a pain to wire in decent stereos into these cars, but it can be done. Had my car ripped up for days doing this....
GD