Just joined the forum and would like to share a quick tip on fixing the Exhaust 30Hz Vibration Absorber on the rear silencer box.
Note this is only fitted on the Diesel model for tickover vibration. Since my car E46 320d 2004 has 140k on it and I've had it since 20k I've replaced a couple of these at £60 each, but I thought I'd have a go this time to see if they can be repaired. The good news is yes.
These are known to have split rubber busing.
Remove the internal bolt M8 size and replace with a longer M8 with large washer to compress rubber. wirelock / threadlock as shown. It has quietened my exhaust down and no problems so far!