The diagram & parts listing for yours is here --> RealOEM.com * BMW E53 X5 4.4i REAR AXLE SUPPORT/WHEEL SUSPENSION

To get there, I just clicked the "Browse Parts" button, then look for Rear Axle, then clicked through the diagrams to find the right area. Will you be doing the work yourself? It's a bit of a big job, and requires a special tool for pulling the ball joint from the wheel carrier.

I'm pretty sure that the wear parts are the same on all the e53 variants. The parts I replaced on mine are as follows:
ball joint -- 33326767748
integral link -- 33326770749
guiding suspension link -- 33326774796
wishbone -- Left - 33326770859; Right - 33326770860