Hi. I had the fan clutch replaced on my '84 280GE about two months ago by my local Mercedes dealer. The part no. listed on my bill (under the name "Power Saver") is 000-200-04-22. That sounds just like the "new" number that you indicated. It was $90, plus $45.90 for labor -- just in case you want to have a mechanic save your knuckles -- it's a rough place to work :-).
Good luck.