Hey Idnan! How's it going!
Yep Idnan's right - I've a propshaft from another BMW but the diff flange fits the differential perfectly. Won't be using it though as I've now got a dct M3 shaft. Think it was from a e38 or e39 v8 (not M5), so you might be able to pick one up on the cheap locally rather than me sending it to you!