I'm trying to find an OEM Nav unit to upgrade my base '06 TL. I know I need the display unit (of course) that also operates the climate controls but what I don't know is what other parts are required for complete OEM Nav. Antenna? DVD module? Wiring harness? What else? I see a lot of units on eBay but it is not clear to me if they include everything I need to upgrade to OEM Nav. Most of the units I see include the display and nothing else. Also, I understand that I need to get the anti-theft code to activate the unit.