I've always used the diff to lift the rear of my X5, E39 and E92. Never a problem. Of course, I'm always very careful not to place the jack anywhere near the diff cover, as QSilver has pointed out above. I also make sure it's centered on the diff. One has to be very careful in jack placement on the diff - I will keep inspecting and repositioning the jack until it's in a perfect position, and then only start lifting the vehicle when I'm satisfied.

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'05 E53 X5 4.4i, '97 E39 528, '07 E92 335i, '16 F86 X6M.