A3000T/UX and a Draco + Alpha Co-procesor.
As for stuff that never saw offical release, then I'd love to get my grubby mitts on an A3000+ and a Phase 5 AMIRAGEK2 if are prototypes hiding in someone's basement.
The UX is nothing more than a standard A3000 running Amiga Unix, which is entirely done by the Commodore A2630 board and then this being intergrated on that A3000 board.
If you hold down the mouse buttons just like early startup and you have this card in the A2000 you will see it will able to start in 68000 mode or 020/030 (A2620/2630) and Amiga Unix.
I'd like to have the A3400, Tahoe recently showed me one, it just looks like a crossover from A3000 to A4000.