To everyone interested in my underride bar. there are 2 part numbers
51 13 0 392 164
and
51 13 0 392 919

I have the second one. My dealer told me that mine will fit 2000 thru 2006 X5s with the aero kit front bumper only. and the ather part numbers fit all other X5s. The dealer also said that they have seen both side by side and said the mounting part is identical but the front part that you actually see is a bii lower to accomodate the lower aero kit bumper. He said they are extremely close though and almost identical. So Let me know who is still interested guys. PM me if you are.
Thanks

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Dinan M3

2006 X5 4.4i Sport Current Vehicle
2006 CLS 55 AMG Current Vehicle
2010 FORD F-450 King Ranch Current Vehicle
2012 GL 550 Current Vehicle

1999 M3 Dinan S3 SOLD
2001 M3 Dinan S2 SOLD
2002 M5 SOLD
2004 X5 4.4i sport SOLD
2007 335 XI Lease ended
2009 E92 M3 SOLD