The 'Order - /Sach-Nr' is a partial part number. Looking at realOEM, I think I need to buy "Wiring Set Pdc Rear 611011 - BMW (61-12-9-244-425)". It's not too bad so I'm going to take a chance.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim