I read entirely the thread which you posted in the link above and didn't see how it was related to the problem checkit13 has.
If I understand the above thread correctly it is to do with problems of the engine shaking either as a result of plugs, wires or even engine mounts.
Checkit13 says he has a rattling sound.
When my mother's '98 ML320 had a rattle underneath it turned out to be the brackets which hold the exhaust/muffler in place.
Another culprit underneath the truck which can cause rattling, again in my mother's experience, is the round, tyre-sized hard board cover which covers the spare tyre which is under the truck. It can come loose and rattles when the truck is under load like when reversing, turning the steering wheel or when the A/C is on.