When I saw King Crimson in 1969 the Poseidon tron was on stage. I remember those metal handles on the side.
According to Ian McDonald, they actually wound up with THREE on that tour. When Crimson appeared at Electric Playground (I believe) in Chicago, there was a suspicious overnight fire of unknown origin, and one of the MkIIs (or possibly both) got an unexpected bath. They managed to dry it out w ith hair dryers, but another was hastily dispatched from the UK in case it was needed. Ian thinks this is the MkII that eventually wound up in the hands of Genesis.
S'truth!
Rick