tdrag97

What I posted to mfrymier is correct, get the TCU from Crevier, get the BT antenna and Fakra connector cable from Randy at eiskits.com (bmw stuff just cheaper).
parts needed
1 tcu
2 BT antenna and conncetor cable
thats all if you you need if you have BMW assist.

The 815 snap in adapter fits and wires into the console fine, directions are on the site for installing this, the "compatability issue" is the Fakra connector at the TCU. The 04 BMW X5 was designed to have Assist or Bluetooth, so in a stock 04, you would plug the cable from the console directly into the bumper antenna if you canned the Assist and went BT. The only thing you need to do to utilize the existing antenna to work with BT and Assist is to get a Fakra adapter cable from Randy that converts the black male end 04 cable to one that fits the white antenna connector on the TCU. thats it, done

You've got to have the dealer code the car. some dealers like mine were lost, print all the articles from the site and discuss it with them first, it should take them more than an hour to do the job

good luck, its really easy once you clear the small BS