ok, I see I am not alone! Yes, good descriptions on the oscillations, in and out, especially when driving at higher speeds on the highway. I guess I'm starting to think it may be a combination of everything (since it vibes while sitting in place AND driving) - I guess I'll end up going thru the entire car. But it just seems like every mopar i ride in, they all have these orgasmic quakes and rhythms.....I'm probably just jealous, because the few GM's of that era I've driven in just seemed buttery smooth and had a more refined feel.