I was beginning to think that was the case, I was going to try 3, 4 & 5 BNC cables on my NuBus Pivot Cards, just to see.

As far as the RCPII/IIsi goes, I started playing with it again with the continuity tester. If pin one is the square ground pin, it matches up with pin one on the Mac DA-15. Pins 2-7 on the RCPII/IIsi conveniently map to pins 2-7 on the DA-15 as well.

That's as far as I got the other day, but I also determined that pins 6, 13 and 14 are all tied to ground.

I'll get to the rest after Valentines Day!