Thought since I'm using all Polk SR series speakers I should post what I've got done. Right now I glasses door pods up front for a set of SR6500's and put a set in the rear in coax mode. I also have a SR124-DVC in the mail to me so I'm going to be making a fiberglass box to go between the front console and the rear seat in the middle.
Here's some pics.
Here's my first shot at bondo, first layer was a little thick
here is the back cut out and a few layers of mat and resin for strength.
Here is a shot with the rings cut out and 2 layers of bondo sanded with 80 grit.
Here is the back with the one on the left I started cleaning up the back edges so it would fit back in the truck flush.
A shot of the grill for my polk SR6500's
And here is my truck