Front...
as in dash or doors? (concert sound added door speakers)
doors, 5 1/4", depth, I believe is less than 2 "
dash, 3.1/2 ", depth, about 1.5".
rear, 4X10"
Doors are very shallow. Dash is pretty open, almost anything will fit depth wise.
If you are looking to replace your dash speakers, be careful of any tweeters that stick out above the basket. Since the dash pad above them is flat, any tweeter protrusion will make the dash stick up a bit, and possibly crack it.
Hope that helped.
Any other ?'s, just ask.