Vern: You should start your own thread about the spark plug wires and coils.

Bayer:
There are 2 different filter sizes, an "old" short version and the "new" long version. As far as I know, you can't buy the short filter anymore, at least from MB. To install the long filter the left side of the rear seat is removed, the carpet pulled up, and a steel plate is removed, usually by using a hot air gun to soften the sealing compound. This is the same procedure used to replace the fuel pump/fuel sender assembly in the fuel tank. You need to do this because there are different lines that need to be used with the long filter, and you can't get to the lines that connect to the pump without having access from the top, through this hole in the floor.
Once you have access through this hole, you do the same thing Vern said to do, but also install these new lines so it all fits. The ends of the lines have strange locking clips, they can be hard to disconnect without the MB release tool, although when removing the old lines, you don't reuse them anyways, so if they get wrecked it's no big deal, just don't damage the nipples on the fuel pump.

Gilly