Maybe I miss understood but I think the OP needs to remove the whole pannel to access the bolts holding the rear clam on and not just a speaker cover. I am not sure that pannel comes out with the harness bar in place.You don’t have to remove the harness bar. For the difficult screws I used a short Phillips head “bit” (with a hex end), but instead of putting it in a drill or socket handle, I used a small closed end wrench to turn the bit (SAE, but I forget what size). Make sense? It’s like a very short, right angled screwdriver. If you put a little tape on the hex end of the Phillips bit you can jam it into the wrench so it doesn’t fall out.
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