For my '01 3.0i, it was part number 16-11-6-755-043. Pierburg (original) came out and a new one went in. Pierburg is now owned by TI Automotive, so don't worry if that is the brand name you see, it is still Pierburg. Cost around $180 on Amazon. I just replaced the pump, and re-used the plastic assembly/sender/etc.

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2001 X5 3.0i, 203k miles, AT, owned since 2014