This is a great X5 navigation retrofit write up with parts lists and pictures. That harness in reference #5 is just the trunk adapter that connects the car's main wiring harness to the nav computer.

http://www.xoutpost.com/articles/all-...system-x5.html

The major parts are the MK3 (which you already have), the display screen, the main navigation wiring harness, and a Board Monitor radio module. Then, you will need a bunch of little parts like brackets, screws, GPS antenna, etc.

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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