I love my X5d and the M57. A perfect mix of performance and efficiency for me, as you mentioned. I always like seeing what people are doing together that extra performance out of the M57. Some of those M50d acceleration videos are crazy. I shudder every time I put the hammer down wondering if this time I shred an axle or blow the transmission or transfer case. Good luck to all.

The wiring/modules/coding isn't done yet so the system isn't complete and I can't comment about dynamic differences.

How exactly did your differential fail?

FYI F85 flanges/axles that I run are beefier than E70 X5M.

Thank you for this thread!
My rear end started clicking badly today. I came across this thread and it inspired me to put the M diff in my 08 4.8i.
From reading this I gather all I have to purchase are 2014+ Rear cv axles as the ones in my 08 won’t work with the M diff flanges? New Axles the only thing I need correct? (If I just want to run it open) I may at a later date figure out what voltage it needs to lock the clutches for more winter traction and put it on a switched relay.. I got the M diff for less than half the price of the failure prone 4.8i diffs. Even with buying new axles I’m way ahead and have a more reliable rear end.

On my setup I swapped diff flanges to accommodate the F85 axles since I stared with an E71 diff. The best advice I can give you is to hop on RealOEM.com and look up the parts to confirm specs.

Make sure the driveshaft is the same length, check the diff mounting bolts are the same, and depending what flanges are on your diff -get axles to match. Once this is confirmed you should be good to go.

I received my E70 X5 M Diff from FedEx yesterday. Unfortunately they dropped it at some point and cracked the side casing near the actuator motor exposing the gears. I can confirm that axles (Trakmotive BM8116) from a 14+ X5 will NOT fit the stock E70 M diff flanges. They are too large.
I ordered another E70 X5 M diff complete with axles this time and a new driveshaft nut. Hopefully it arrives intact and I can get my vehicle back on the road.
Any tips on the 50mm driveshaft nut besides heat and muscle?

I received my E70 X5 M Diff from FedEx yesterday. Unfortunately they dropped it at some point and cracked the side casing near the actuator motor exposing the gears. I can confirm that axles (Trakmotive BM8116) from a 14+ X5 will NOT fit the stock E70 M diff flanges. They are too large.
I ordered another E70 X5 M diff complete with axles this time and a new driveshaft nut. Hopefully it arrives intact and I can get my vehicle back on the road.
Any tips on the 50mm driveshaft nut besides heat and muscle?

You don't need muscle, just the right sized wrench or tool. It's reverse threaded. As I suggested looking up parts on RealOEM, I would also suggest looking up the service procedures for removing the rear diff. It's best to understand the tools needed and the process before starting the project.

Thanks for the heads up on checking realOEM. I would not have thought to check driveshaft length as I assumed they would be the same since the transmissions are GA6hp26z.
According to the site my driveshaft is 18mm longer than an x5m. So I’ll have to figure out a workaround.

Thanks for the heads up on checking realOEM. I would not have thought to check driveshaft length as I assumed they would be the same since the transmissions are GA6hp26z.
According to the site my driveshaft is 18mm longer than an x5m. So I’ll have to figure out a workaround.