Okay friends - here's what I've learned.
This is the part I need:
These parts are supplemented by this part (t-lock 900 039 002 02), which I think are meant to convert floating rotors to fixed, by locking the rotor to the hat:
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I have feelers out to Doug at VCI, and Mike at PMB, but in the meantime - if I decide to assemble my project as non-floating do I need 12 t-locks, or only 3 or 4 per disc, just to lock the disc in position.
Thanks to Bill V for the info, images, and knowledge.
Bill K