Im gonna replace my front speakers today and put some in the back in the stock housing, what sizes will I need for both, and are there some speakers that are too deep?

 

6 1/2 would fit fine, and 5 1/2 will fit too, but you'll need the cup.

 

6 1/2 all around

 

I have 6.5 all the way round. In the front I kinda had to take a hammer to the plastic cup thingy holding them in for the magnet to fit. If theres a will, theres a way to make anytihng fit. When you replace the back speakers its a Biach to get them in without takin off the panel. good luck