- The place I obtained the front diff (for E83 X3) was LKQonline
bc they tag every part with VIN and proved with odometer reading.

This way you know for sure the age/mileage from the part.

This not a job you want to do again.

All the relevant tips are in the DIY (for X3) that I posted above.

Idk what you ordered from Rock Auto, but for this job, I use only BMW parts...

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT