I replaced all of the rear end wear parts.
These are what I used for the rear lower control arm
BMW X5 E53 00-06 Rear Lower Arm Bush Kit Front & Rear Position x2 - PSB 653 654 | eBay
You could also just use a OE/OEM bushing for a lot less. I just wanted to go poly and I was doing it all myself without a hydraulic press.