Apple A/UX install

Anyone on the list have experience installing A/UX on a 68k Mac? I'm running into some very odd issue trying to bring up my Centris 610. The Centris shipped with a 68LC040 processor and I've upgraded to a "full" RC68040 CPU, since that's a requirement for A/UX. The CD-ROM drive is one of the units known to be compatible with A/UX. The FAQ claims that the installer understands third-party hard disks (unlike the MacOS installer) so I'm trying to use (variously) an older IBM Deskstar 850MB and/or Fujitsu 500MB SCSI drive for the install target. Here's the odd part: With the original Apple-branded OEM Quantum drive (which I do not want to overwrite) on the SCSI bus the installer recognizes the CD-ROM and is willing to begin the process. However, with any of the third-party hard drives in the system it is unable to recognize _anything_ on the SCSI bus - doesn't see the hard disk or the CD-ROM. I've checked and double-checked the jumpering on the hard disk and it's not conflicting with the CD-ROM. Both the IBM and Fujitsu are fairly run-of-the-mill 50-pin SCSI units. I've never had issues in the past with non-Apple drives hanging the bus or preventing access to other devices, so this one's really a head-scratcher. Any ideas what might be throwing the SCSI subsystem for a loop? Steve --