Just wondering if anyone knows the difference between units, the dealer gave me model #4E0 910 593 D as been the unit for my car. I have seen a few on Ebay for sale but the numbers don't match, does it have some thing to do with the wiring and the MMI system ?

 

It has something to do with the receiver's frequency, or it could be a completely different model that communicates differentely to the MMI. I wouldn't get another module that doesn't have the exact part number for your car. These cars don't like running the wrong module, crazy crap happens.