I would convert to a more up to date stereo and put speakers in the rear. The sheet metal on the rear deck is very stout and it is difficult to cut. I did that to my 1969 220D and it worked great. I assume your car has the fuel tank below the trunk, if not it can be a problem. I installed 5" in the rear and installed 4x3 ovals in the bottom dash covers in the front. I would not cut door panels or other stuff. If you remove the center speaker, install some black cloth on a screen in place of the removed speaker. If you don't do that, light shines through at night and is annoying.

Henry

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