RealOEM.com * BMW E53 X5 3.0d SLIDING LIFTING ROOF FRAME

Repair kit in this diagram is #11, not expensive (but more so in your part of the world). Not sure if this part number includes the part broken on yours, but it would be a good place to start. It is called a repair kit for the frame assembly. There is another part number listed elsewhere that repairs the plastic rail, one per side, in particular the plastic guide that is part of the tilt up mechanism. That sounds like what you need, but it may just be that the part numbers have been superceded/changed up.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue