I think I know what you are refering to. It is also on the 123 and 126 series cars. One is located under the battery and the other on the side of the car. If that is it the if it were to break while driving(most likely on a turn) your car would roll more and not be too stable going down the road, needing constant steering imput, but it should be fairly drivable. If it does break then im sure the rusted panel could be cut out and a new one welded in its place, just about anything is fixable. Ive had the front swaybar mounts break on my 16v many times, and the car rolls more in turns and feels twitchy driving strait down the road. Take a look at it and determine what about it is loose, maybe the bushing is worn out, or a screw. The 6.9 creates a lot of torque and is heavy so the sway bars(rubber parts too) work harder than in another mercedes, putting more stress on the parts. So after 20 years and 200k miles the rubber or other parts may be worn out. Hope this helps.
1985 190E 2.3-16
1957 220S(running one day, I hope!)
[This message has been edited by AMGmercedes (edited 07-20-1999).]