The door panel is easy to remove. On the '97, there is one screw under the door edge reflector (pry it off and look for it), and two screws by the power locks switches. Remove all three, and pry off the trianglual plastic 'sail' panel above the door panel and ahead of the window glass. Then use your fingers to gently but firmly disengage the plastic clips that run along the sides and bottom of the door panel, and lift the panel out vertically to disengage the top clips. The speaker is mounted in a delco tray made specificly for this opening. I mounted a 5 1/4" 3 way Sony in each door by copying the shape of the tray onto a piece of plexiglass, and cutting out the hole for the speaker in the plexi.
It is one nice thing about the GA, that with not alot of effort, you can put in a very ince set of aftermarket speakers.
If you are still having trouble getting the door panel off, contact these people:
Crutchfield
They make detailed information sheets for whatever make of car you want, telling how to install speakers and head units into your specific vehicle. They've always been happy to send them, when I've called their 1-800. (They're also a decent source of speakers and the like).