3BEP6

Hey, guys, tried to search but came up with nothing. Did anybody try to swap 550i 2.81 diff(6speed) for a 3.46 one(530i auto)? They are cheap and would make a great upgrade to 550i. I'm not ready to splurge on a qualife even though it's the final goal and my car is a daily so I do not want to put it out of service for too long. I'm curious if it is a direcT figment as far as mounting it and if I would need anything swapped besides input and output flanges. Any information is greatly appreciated.