Finally took a decent ride with my son and I've got a few to-dos.
I'd love some advice on addressing the distortion that seems to be coming from the passenger side of the rear deck.

I've done some searching/reading and I see some suggest that the rear deck needs to be removed (through a bit of a process). Is that the only way to get to this speaker?
Is the speaker an integrated system with the subwoofer?

Any advice on how to replace/upgrade this would be appreciated.

I'm assuming that you don't have fold-down rear seats which might make the job easier.

.I had to replace the rear speakers on my 96 Infniti G20. (I know that is a different car from a different manufacturer.). The rear speakers were "sandwiched" between the trim of the rear deck and the metal of the rear deck.

I don't have rear deck speakers on my C230, but I had to replace the motor in my rear sunscreen. The design looked similar to the G20. Based on that experience, I think you will need to remove the rear seat to access the speakers.

Thanks, Kevin.
Vehicle is new-to-us, so I wasn't sure about the seats. I just checked and I don't see any ability to fold down.
I DO see a number of nuts on the bottom side from the trunk. Is it possible to access anything from the bottom?
I also read a few folks suggest that you can pop the screens/covers off. I can definitely pry from the one side, but I didn't push it. I hate breaking tabs... Is it possible to simply pop those?

My dad is a retired Master Ford tech that specialized in electrical work. I can probably pawn this off on him, but I'd want to have speakers in hand so that I could do this in a single dad-adventure.
Can folks identify what speakers I'd want to get for the rear deck? I'm reading mixed things.
Again, this is the HK with the surround option. I'm hearing distortion that we can clearly isolate when directing all the sound to the rear, passenger side.

I have speaker covers in my rear deck even though I don't have speakers in that location. When I had the rear deck off, I think one of the speaker covers fell out. So you can just pop them off. It's been over a year since I did the work, so I don't remember too many details. I suggest that you gently pop off one of the covers and see if you can access the bolts. Here's a link to the instructions I used to remove my seats: https://www.pelicanparts.com/techart...eplacement.htm
It is not extremely difficult, but I can understand why you would want to avoid it if you can.

I bought the interface needed to install my navigation unit from Crutchfield. They sent me an installation guide for the W203. Unfortunately it covers everything except the rear deck speakers. If you buy equipment from them, their staff is very helpful. I checked their web site and they had some photos of work they had done on a W203: https://www.crutchfield.com/S-9qvtEe...-Speakers.html (Choose the correct year and body style of your car and then scroll down the page to the "research photo" area.)

One of the photos appears to be of a rear deck installation with the rear cover off. I don't think that proves it is necessary to remove the rear seat, but it does tend to support that.

Thanks, Kevin.

Crutchfield was my first stop. They state that they don't have any compatible speakers and don't provide any information for the rear deck.
Other online stores DO, but I've had very good luck with Crutchfield in the past and that's part of what made me skeptical and looking for more knowledgeable source(s).

I saw those pictures as well as a few others with different rear decks.

Here's a little more information :http://benzbits.com/w203/RadioOptions.pdf There is not much detail, but it appears that the passenger side of the rear deck contains a surround speaker and the drivers side has a subwoofer and a surround speaker in 2003 and earlier models. It appears the sub was removed for 2004 and later models.

This may help too: https://www.benzworld.org/forums/w20...e-how-can.html

And this guy seems to confirm you need to remove the seats: https://www.benzworld.org/forums/w20...rear-deck.html

I'm afraid I'm out of suggestions at this point. You may need to "bite the bullet" and remove the seats. When I removed my rear shade, it was stuck in the upright position which left very little room to wiggle it out.. At least you don't need to deal with that probe..