Chassis and cradle is the same between non M E85 and 86, whether facelift or not.
Diffs from many different BMW's are an exact swap. I will be running an X3 diff for the first bit of this season to see if I like it.
I have used an E46 diff in the past as well as an SMG diff from a 3.0si.
There was a website around called BokchoysBMW for a long time with an interchangeability list on it, unfortunately it's offline now.
https://www.e46fanatics.com/threads/...-gone.1288847/