17 or 40 pin?

[No10]

I first tried to connect my mp3 unit to my 2001 X5 over two years ago using a Soundlinx adapter, which uses the CD bus lead, but the quality was terrible. I haven't driven the car much in that time but now it may become my main transport so want to get the sounds sorted.
I contacted Soundlinx and they said this was a common problem with X5s due to the original BMW bus lead? The offered to sell me a replacement lead but need to know whether it should have a 17 round pin or 40 flat pin connector. To save me taking the radio out (for now) does anyone know which it will have. It's a non-nav business radio cassette.
Thanks for any help in advance