I changed the fan clutch on my '98 e300td a few days ago and found this article to be extremely helpful. Thanks. I installed a Sachs fan clutch and it works well and is about $200 less than the lowest price I could find for the Mercedes fan clutch. My experience:

1. A telescoping magnet is probably an essential tool for most of us. I dropped the 8 mm socket twice and a ratchet once and was rescued by the sears magnet I bought several years ago for about $5.
2. Mercedes has changed the bolt used to attach the clutch to the water pump. The original bolt was the one with the 8 mm head pictured in the article. The new one has a T55 torx head. Either by design or accident, the 8 mm stubby socket works on the new torx head bolt. This socket has a little more play than I would like, but it still works. I think this socket is the essential tool for this job on the '98 and '99 diesels.
I did find (but did not buy) at Amazon an "E-Z Red super low profile torx bit set" which has a T55 torx bit that would probably work for screwing in the new bolt. It is not a socket; it is turned with a wrench; a 17 mm I believe. The 12 bit set costs about $35.
3. I used a cheap ($10) Duralast breaker bar style ratchet and the 8mm stubby to break (the initial loosening) the 8 mm bolt. I bought it at Auto Zone. It has a very low profile, and the half inch, foot-long pipe extender I use for my lug wrench fits over the handle. This gave me extra torque and got my knuckles away from the fan in loosening the bolt.
4. Don't try to work from the side. Work from the top of the radiator.