I would just buy an aftermarket fan from Pepboys. I look at it this way: you get a new fan for far less than a MB replacement, it comes with a new relay and wiring harness, it is newer, so it likely operates better (i.e., more quiet and better design to the fan blades), and you can buy a larger one that pushes more air (which will give you better a/c operation and engine cooling). I don't think you can loose. This is what I plan on doing on my car, especially since I can buy a huge fan to blow lots of air to give better performance of my r-134a-converted a/c.

Good Luck,

Greg
'84 300D