you have the older version of the 722.6 which has a failure point where the front planetary gearset loses alignment due to a worn bushing which then causes it to bounce and make noise.

its best to stop driving it and get it rebuilt. Otherwise it wont be too far that you have a transmission filled with metal grit.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)