hi there, just read your thread and guess what? i just went over the exact same problem you have......didnt want to crack for the expensive new clutch.
so i went to the self serve yard after taking some careful measurements,and found that with very minor modifications that for my 1980 300d a fan AND clutch from any mazda or mistubishi truck just about bolts right in. i did this yesterday and it works great...also alot quieter then having a directly bolted on fan(which i had before) .....the diam for the fan blades themselves were only about 1/2 inch smaller on these trucks,i was going to try and use my old fan and modify the clutch but surprise surprise, didnt even need to do that.
the only two small mods were: had to slightly enlarge the bolt holes on the hub itself,pattern was the same but holes were a little smaller. and the 2nd,
since i used the fan from the mitsubishi truck, the blade pitch was slightly greater,and it was just catching the crank pully and ticking a little (the blades are plastic) i filed them down just a tad, and now it works great!!!!!
both mods took a grand totoal of 5 minutes hope this helps