the door panels are secured by 2 screws hidden behind the fake wood trim on the door handle. then there are I think 8 plastic clips that pops out with force. Once door panel is removed, you will see the speaker and it is secured by 3 screws, unplug the connector and loosen the 3 screws and you can take the whole speaker assembly out. You will have to reuse the speaker assembly housing. The bose speaker is secured by 4 screws onto the housing. Everything is self explanatory once door panel is removed.

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98 ML320 (gone but not forgotten)