G888 modules for TC11/TU56

[Ashley Carder]

I just acquired a TC11 unibus controller for a TU56 
DecTape drive.  The TU56 is on the way.  Both of these 
are going to be fixer-uppers.  Upon comparing what's 
in the TC11 to the engineering diagrams, the first
thing I noticed is that it's missing all five of the
G888 modules.  Does anyone know where I can find some
of these?  Can someone tell me what's special about
these "Manchester Read/Write" modules and why all of
them would be missing?

Thanks,
Ashley