3.0 is different as it has the sound generator hole and a wider neck
http://www.realoem.com/bmw/enUS/showparts?id=BT53-USA---E85-BMW-Z4%203.0i&diagId=13_0995
Mine was gone when i bought mine. Ordered the part for £30. Its fiddly to fit if you have big hands, but only took maybe an hour (that was for me, and im s**t at fixing things that require patience)
Agh, Mine is also a 3.0i engine, did not realise they were a different size, I've got the right part fitted, the images I just pulled of the internet to show you the right part - will look more closely at the part numbers next time, sorry about the confusion.