Almost any 6.5" speaker with less than 2 11/16" depth will fit, if you let a professional installer do it. While you're at it, may I suggest, component speakers in the front, with the tweeters aimed up at a 45 degree angle off the door sails, pointed towards the rearview mirror? It sounds odd but it works - trust me.
If you don't want to cut metal, you can get perfectly fine 6x8 components - if you're willing to pony up the bux... Boston makes rc820s which are dynamite drop-ins for the contour - they just cost about $320 list. A pair of those up front and a pair of the RM6 components in back on an adapter plate will fit without any metal cutting.
Don't forget to dynamat while you have the doors off!
