I have a (fairly rare, I think) Model 106, which basically consists of eight 44
key pianos built together in a "fold down"assembly.  Half are orange, the other
half tan.  Each has seperate outs for headphone and amp out (I think) and sport
the model number 106P.  The serial no.is 60078 for the entire set-up.  Each
piano,of course, has it's own number, if you're interested I could send them to
you as well.  There is a switchable patchbay which activates which keyboards
and which mode they'll be heard in.  This is located by the teacher.  It appears
that a simple plug and a few screws would remove any of the keyboards, they're all in pretty good shape, but I can't bring myself to tear it apart.  
Oh, there is also an eight way amp above the main wheels that is the main on-off switch as well.  I've had these for some time, and am considering selling any or all of these beautiful boards.