Where is the OEM trunk "plug" for the CD changer 95' C220 ?

Dig around the recessed area of the right side of the trunk, behind the wheel housing and the rear brake light, near the side fender. The CD player is typically hung vertically in that small side trunk space, and the cable is normally coiled under the grey trunk cover on the side. I believe I found my cable by pulling up the trunk liner on the rear right fender area, and it was tucked down below, almost to the spare tire / battery recess.

My dealer had a third-party prefitted mounting panel that fit perfectly over the side recess area, covered with the same trunk fabric used everywhere else. I only had to slide the CD changer vertically into the rectangular cutout, snap in the cables (two of them), then simply drop the changer and mounting panel on top of the recess, leaving only the very top of the changer showing. No mounting or drilling or hassle; looks like it came from the factory, completely the same fabric, changer placement and look of the factory-ordered accessory.

I'm not sure they used the combination radio/telephone (keypad) system on yours as they did on my 2000 C230K, but that's where my cable ended up being stored -- in the right rear recess near the tail light, under the trunk covering.