What I replaced on mine are #02 ball joint part #33326767748 (one per side) I paid $40.12 each from Rocky Mtn European (BMW Parts, Porsche Parts, Audi VW Mini Volvo Saab Mercedes Auto Parts - RM European Auto Parts)
and #11 left wishbone part #33326770859
and #11 right wishbone part #33326771860
I paid $100.57 each also from RM Euro. There are many choices but I chose the Lemfoerder for both. There are cheaper and of course more expensive replacements.

Here is a link of the parts diagram. Penske Parts - Technical Diagrams - E53 X5 3.0i (M54) SAV

Hope this helps.