There is a nice set of instructions for replacing the fan clutch on this website:

PeachPartsWiki: R&R of the Viscous Fan Clutch

You should read this paper. I think you need the shortie socket, and the thick, bent wire locking tool is extremely useful (both are shown in photos in the paper). I found it easiest to work from the top of the radiator as opposed to the side. You need a low profile ratchet as there is very little space between the radiator and the bolt that holds the fan clutch on the water pump. I put a piece of thin cardboard against the radiator to protect it from the tools I used. You should get a magnet that's is on a telescoping rod or handle as you my drop a bolt or socket. You need it to get whatever you dropped back.

I put a Sachs fan clutch on my car (a '98 E300) a couple of months ago and I recommend it. I bought it from Pelican parts. As far as time is concerned. It took me two and one/half hours to do the job. I'm 78 years old and do everything kind of slow these days.

Mercedes has changed to bolt that holds the fan clutch to the water pump from hex headed to torx headed. You can still used the shorty hex socket to screw in the new torx headed bolt. Either by accident or engineering, Mercedes allows use of the old tool on the new bolt. I choose to think it was by accident, because Mercedes engineers seem to enjoy making life difficult for DIYers.

The special tools are available from Samstag sales.