My buddy drives an 02 X5 and his tail light brake bulb went out today. If someone can tell me how to replace it that would be great. thanks.

Very easy; just remove the side panel in the trunk on the side the light is on and you will see twist connectors sticking out of the light housing. Just twist and pull. There is an issue with the tailights however; the contact areas are made of aluminum, and corrode and short out. Instead of replacing the unit (around $500), take it out, find the area shorted, sand down, and fill in with solder. I did this and it works great.

And sometimes you can just sand off the contact and it works without the whole soldering bit.

owners manual?