That's interesting. I had read that any difference in track width between M3 and normal e92's was due to wheel offsets.
So this meant most suspension arms are easily interchangeable apart from the 1 or 2 (marginally longer or different damper connection)
The rear hubs aren't that different either. I kinda assumed any difference in driveshaft lengths would be down to the width of the diff.
Hopefully someone knowledgeable will be along shortly!