There might be space under the passenger seat. If so, what I did in other cars is use metal plates with coutnersink screws in them in such a way as to match with the brakcets of the changer. Then I attached the plates with double sided tape to the floor of the car and cut slits in the carpet to let the screws through. I wouldn't feel right drilling holes in the floor of the car. It's not the most secure setup, but you'd have to tear the carpet to take the changer without undoing the nuts. I used washers to level the changer. Sorry if the tenses are off.

If there's no space under the passenger seat, it'll have to go in the trunk. You can hang it from the deck but that makes it visible when the trunk lid's open. I have mine vertically in the pocket behind the right wheel. It's about 2" above the floor of the pocket because the pocket is a certified flood zone. My car came with a Becker changer so I had a bracket to use with the replacement Sony RF changer. All the bracket is is a T-frame that bolts to the horizontal surface inboard of the pocket. It's made of pretty thick metal (1/4" ?) with continuous welds. It's actually an angle section welded to a flat section so there's a long weld line, not the edge of one flat section into another flat section. I guess that prevents it from vibrating independently of the car.

As for wiring, the changer will have a couple of thich cables that should reach the area behind your Becker. Extensions are available from Radio Shack. You plug the antenna cable into one, and the other plugs into your Becker. The changer will need switched power, always live power and ground. You can probably tap into the Becker's wiring for those.

Then there's the matter of the controls. I prefer the kind with a wired remote. I leave mine in the tray behind the shifter. Fancier units have a fixed display and a remote control. MB dashes don't have extra space for the display. I've seen folks stick the display near the shifter. Do you really want to use double sided tape on that nice veneer?

Email me privately if you have more questions.

Sixto
91 300SE
81 300SD