[srdjs1]

Te reason crutchfield gave you 3 diffrent sizes for the front doors is beucase for the 5 1/4" and 6 1/2" you would probably need the adapter plate for them to fit in the opening. Otherwise the 6 3/4" speakers are going to give a better fit for the front.

For the rears the same thing applies for everything upto the 6x9 speakers would use an adapter plate.

For the best sound quality through experiance I have found that regular round speakers will distort less than the oval types. I would try to find a set of 6 3/4" speakers that would fit both locations for a ballanced sound and if you still want more low end go with a sub sized to fit your needs.