If you've removed the driveshaft, you could have it not aligned correctly. There's colored marks to line up the driveshaft from MB. If it isn't balanced, it's going to cause a vibration.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k