If there is a 6x9 hole in the front, you should be able to fit most 6x9 speakers. The reason crutchfield doesn't show some of them might be because they could be too deep for the door. The doors are a lot tighter than a rear deck, they have a window that has to be able to move up and down without hitting the speaker.
If you can't find a 6x9 speaker that will fit, you can get an adapter plate so you can fit 5.25" speakers up there. It won't be as much bass, but with aftermarket speakers they usually don't have a lot of bass anyways. It might be easier to fit, and circular speakers have better sound quality as well.