Well if the speakers are original...they are probably dry rotted around the cone edges. This will make them sound like [email protected]
It is not that tough to take the door panels off and yes you have to take them off.
You have to take out a few screws in and around the arm rest...seems like you have to unthread the door lock if yours has the kind that has a plunger by the window ( I have an 87)....and the bezel around the door handle comes off.
Then the edges of the door panel pop out with a little force as they are just held in with those white ribbed fittings...then the door panel lifts up a bit as it rests on window lip....and if you have electric locks and windows you can disconnect the connector behind the panel.
Just buy new speakers...they are cheap enough at Wamart.