I'm not familiar with the 300SD setup of the 617, but I can tell you that you may want to replace that mount.

On my 300D I replaced both mounts after I replaced the oil cooler lines. The driver's side mount was fine. Not collapsed and probably could be used again.

However, if the mount on the driver's side fails and starts to collapse. The belt from the AC compressor can rub against the rubber oil cooler lines and start to saw it apart. This is very bad as you can lose all of your motor oil if you're driving at highway speed which will causes complete engine destruction.

My passenger side mount was rotting apart. It had been drenched in motor oil for years from a leak near the turbo. I cleaned the area and put the new mount on, but I can only guess how nasty it will get as I have yet to fix the leak.

Replacing the mounts as well as the differential and transmission mounts has been one of the best things I have ever done. Nice smooth driving, the car coasts better, and no more jolting when I turn the engine off!

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-Typos courtesy of my mobile phone.