The Quadra 610 and Quadra 650 were anticipated in 3.0.1, so the kernel recognizes their machine ids, but the installation floppy did not contain the necessary enabler. Keep in mind that A/UX will not work with 68LC040-based Quadra 610 computers. The low-end Quadra 610 (8/160) has the 68LC040.
Here's how to get A/UX running on a Quadra 610 and Quadra 650:
1. Make a copy of the A/UX install boot floppy.
2. Put the enabler for the Quadra 610 and Quadra 650 on the new install
3. Boot up and install normally.
4. Boot off a boot floppy or boot CD. Install the Quadra 610 and Quadra 650 enabler on the A/UX boot partition.
Things should now work fine. The only glitch is that the A/UX Finder won't give the correct name for your computer in "About This Macintosh" since their final names were not available when A/UX 3.0.1 came out.