This is a very easy and quick job, and there is a lot that has been written about it in this forum. All you really need to do is search on "remove rear door panel." Once the panel is off, you will know what to do, based on what you see.

The window does not need to be down initially. Once you have the door panel off, just cut the braided steel regulator cables and pull the window down by hand until the plastic jaw that connects the bottom of the window to the regulator can separated.

On the underside of the jaw is a black plastic snap-in strip that you remove to allow the regulator's plastic 'lift' (I don't know what it is properly called) to slide out of the jaw. You can then push the window back up, and it will stay there until you need to bring it down again to attach the new regulator. (At least that is how it was with my car.)

If you are replacing the motor as well as the regulator, be aware that the motor's power cables connect to the back of the window switch in the door, which you will need to pop open to detach the old wires and add the new ones. There is a color-coded re-wiring diagram inside the switch; be sure not to misplace it, since all the wires (5 of them, I believe) will jump out as soon as you open the switch.

If you buy aftermarket regulators on EBay or elsewhere, be prepared to cut off the new regulator's wire terminals and splice on those from the old one. The OEM terminals in my car are hollow cylinders, whereas the new replacements were round rings. Takes all of 5 minutes with a wire stripper and electrical tape.

Good luck.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black