Pretty rare that a clutch goes - did you just pick up the 6MT X or have you had it for a while?

Anyway, have you tried the dealer to source the clutch kit for you? If RockAuto is giving you the wrong part, send it back and get your money back - for your 6MT I'm finding part #
21207546378 - did that part cross reference with the Luk kit you bought from RockAuto?

You can get the Luk kit or Genuine BMW kit for $20 more
https://www.ecstuning.com/Search/Sit...h/21207546378/

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards