[Phx Mike]

Hope you can sort it out easily and it's not a big deal Karl. If it's not vibrating sittting still with the clutch in, then (as you note) it's not the engine or flywheel. Sounds like it is shaking at various vehicle speeds as you go through each of the gears, so probably not wheel imbalance (since that would be limited to certain vehicle speeds, or get steadily worse as you gained speed). This makes me think it is transmission or clutch related. I would check the transmission mounts and u-joints and if all seems secure there then maybe the clutch disk?