If you want to keep the performance of the system, your replacement speakers will need to have a 2 ohm impedence. Two speakers that I know of right now are the Infinity Kappa 62.7i and the JBL GTO627 speakers. Both are 6.5" 2-way speakers that come with adapter rings for a 6.75" opening.
Looking at the door, two spots where screws are located are visible. The first being under the wood trimmed door handle (green circle). Pop that cover and you'll see 2 screws. The 2nd screw location is where the door lock and silver release lever is located (red circle). Pop that cover and you'll see the screw.
Next, you'll need to remove the sail panel (next to the side view mirror). If you pull it from the edge closest to the glass, it'll pop off with a little effort. Once it is off, you'll see the screw to the far right (blue circle)
Once you've removed the screws, use a panel tool or a flat blade screw driver to lift up the bottom edge of the door panel cover, enough to get fingers under it. Then you'll just need to pull the panel away from the door. Careful not to pull so hard you rip or break any wiring. You'll need to disconnect the wire harnesses for the safety light, as well as the window, door lock and mirror controls before being able to completely remove the door panel.
After the panel is removed, you'll see that the speaker is mounted to the door panel with rivets. Simply drill out the crown of each rivet and the speaker unit will come right off. You can use wire harness connectors (Scosche or Metra makes them), or you can clip the wires (just be careful to keep track of which is your positive and which is your negative) and use butt connectors to connect the wires to the new speakers and install.
If your new speaker has an outboard crossover unit, you'll need to find a location that you can place it. If you look at the topography of the door panel cover, you may see a place that will allow you to stick it to the door panel with some industrial strength double sided tape, or you might have to do the same thing, but inside of the door panel. For my install, I placed the crossover unit inside the door panel.
Now you're ready to re-install the door panel cover and proceed to the rear doors. The rear doors are pretty much exactly the same as far as removal of the panel. The only difference is the screw that's located behind the sail panel on the front door, is located on the top, front edge of the rear door. It is covered by a "button". Remove the button and see the screw head will be visible.
