When was the last valve adjustment done?
Are the engine mounts original? If they are their probably due. Top speed sounds about right, are your fuel filters and air filter fresh?

Try posting this in the diesel forum. Their seems to be nothing they don't know about these over their.

Describe the "shaking" does it sound like it's missing? Or does it sound normal and just shake?

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200