What are you trying to ask?
The rear oxygen sensors are located after the catalytic converter's Usually under the vehicles floorboard.
you cant
2005 has older technology running it and 2006 has better and improved technology to make it run even better but basicly they are the same
If your x5 is equipped with a CD changer, it will be located behind the driver's side panel in the very back. This is not standard equipment, however.
I have a 2002 X5. when mine would not start, I could not even jump it. The battery checked out ok. I found the steering lock has something to do with it. Try turning or repositioning the steering...