door speaker size

Does anyone know what size the door speakers are in a 74 Mercury Montego? The factory ones are shot and I'd like to upgrade.

As fas as I recall, a 6" mid fints fine in the opening. I always thought the 5-1/4" round was the correct size, but about only thing I'd worry is the depth.
My car is all apart right now, I can not recall what the max depth for a speaker can be.
One suggestion, get some foam baffles, {basically looks like a soup boam made out of a foam product], will help a little from what I have been told for sound.
[addsig]