You might give IPT a call. The modify BMW transmissions. I suspect they would be a good source to get reliable input. There is also a good source on this forum. I don't know his handle but if your search some of the transmission related threads I'm sure you can find him and send him a private message. I'm pretty sure the at least the bell housing and torque convertor on the 4.6 transmission are different to accommodate the HP/TQ of the 4.6 but that doesn't mean it won't fix.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas