Thanks. To be more clear:
Bolt #3 on the car's left hand side (not diagram's letf) broke and the diagram shows it mounts to the diff. It actually caused the diff to move a little causing more noise. It mounts the diff to some part of the car( perhaps connecting it to some part of the exhaust system). Part number: 33176760343 (Hex bolt with Washer). The invoice also calls it "LOWER DIFF BOLT" (and matches up with the part number #3 in the diagram). Yes it is a pretty beefy looking bolt so it was somewhat worrisome it broke.
2008 BMW M3 Coupe / 6MT / Tech / Cold / Premium / EP Sound / iPod:USB / PDC