Interesting. Would a bad mount cause the engine to actually move as it shifts, though?
And the vibration is a lot milder in neutral, but is still present. Initially when we pulled the old center mount and saw it was worn, just not really bad, I thought I might have a secondary problem with bad spark plugs or something, since you can feel the vibration through the whole body of the car; I haven't checked them yet, though.
However, now my concern is that clicking/clanking sound on shifting and the whole engine moving before my eyes. I'm no mechanic, but I also don't think the tranny itself is bad as it actually shifts like it should and holds steady during driving. The RPM's also remain ok.