The electronics and general cabling for all the cars are the same. One major difference is that the E53 actually has official parts for Sirius, since it was available from the factory or as a DIO in later models. I do not know the part numbers, but give a dealer a call. They should be able to pull all of the parts necessary. Then you can make the call whether to go with an OE antenna and antenna cable or aftermarket.

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2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input