I recommend you go to http://www.crutchfield.com/ and click on the "What Fits My Car?" link. Enter your vehicle information at the prompts, and the crutchfield database will give you a list of everything that's a perfect fit, or can be fitted with minor modification.
According to their database, 6.5" speakers can't be easily fitted in your doors, but they have a lot of 5-1/4" speakers that will fit with minor modification. (If you buy these from Crutchfield, they'll include a 6x8 -> 5-1/4 adapter bracket that makes installation pretty simple.
Most likely, to put 6.5" speakers in your 6x8 openings, you'd have to cut the opening out, and either buy or make some sort of adapter to move the mounting holes to the proper location for the new speakers.
if you will not need to make any changes to your door. a 6.5 will fit if you build a 7x8 plate about 1/8 thigh. cut a hole for the 6.5 and place the plate then the speaker on the door. use four screws to mount the speaker and plate to the door. then use some silicone or something like around the plate to seal it to the door. this will keep the back wave form mixing with front wave. if you want a little more bass then use some foam. make a ring and place it round the speaker. when you reinstall the door panel it will help keep the sound from the going in between the door and the door panel for more bass .
hope this will help.
the stock speaker size is a 5x7/6x8. u could use an adaptor plate for the 5 1/4" speakers into the stock openings but i wouldnt try fitting 6 1/2" in there. ur best bet would be getting a 5x7/6x8 component set. mount the woofer inside the stock location and mount the tweet on the sail panel. i know JL and Infinity sell a component speaker set like that.
the jl audio xr570csi are the best 5x7 compent set out there if you asked me. but doing a 6.5 in the door works very well you want something like a three compent set. i am running a 6.5 in the door and 5.25 and tweet in the kick. sound great. a 5.25 in the door is easyer but the 6.5 isn't that much harder. but for time and money the xr570csi will work and sound good.