Fan, Clutch, Water Pump
Try this:
http://www.e9coupe.com/forum/showthread.php?t=6274&highlight=clutch
Basically, the answer depends on what you have in the car right now:
1) Original- friction ( Yes, I have this one- it works ; even with a/c.)
2) Viscous clutch with 4 bolts and corresponding water pump flange.( Visible fins on the rear of the fan)
3) New or upgrade with single nut on the pump shaft with adapter.
Looking at the picture of the fan you asked about, it looks like it's for item 2. But you can find the red ( tropical) one on occasion from other models. If you're having water pump problems, the upgrade is prefered by many members. Some vendors like Mesa sell a conversion with all the parts.