Replace Rear Door Speakers and Remove Rear Door Card in a C218 W218 X218 Mercedes. I didn't see this video posted anywhere but it is different than the front from the outer card in.
Outer most door card no access panel, an additional screw, more wires to unhook versus the front.
The front you can drill out the the rivets for the speaker itself. In the rear you will have to destroy rear speaker, drill out the rivets from inside, and either fabricate, print, or reuse the old speaker as a mount.
You will need 2 star drivers, one recommended to be a swivel for the inside door handles.