Doesn't look like OEM, as you can see by comparing to the pictures and diagrams in the long DIY thread. I expect it is a UHaul-sold aftermarket, though it does look better than most aftermarket in actually mounting to the unibody through left and ride side 'supports,' the two shafts in your picture. What does the fine print on the sticker on the right side claim? Just your standard suit-avoidance warnings, or does it claim hitch and trailer weight ratings?

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2006 X5 3.0 6-spd w/Evo UUC ssk
sport/premium pkgs
born Valentine's Day, 2006.