What year and model? Some of these have engine shocks that are designed to minimize engine shake at shutdown.
Most old MB diesels will see a benefit with new motor mounts. I installed new motor mounts in my 300SD last week and have seen a nice improvement. Less shaking at idle. I have the new engine shocks to replace next. I noticed at least one of them had the mounting torn loose. Have to replace the shocks and the mount kit on these now. They come as seperate parts.