What's up with A/UX?

I've been using Apple products since our family got a used Apple IIe to replace our TRS-80. I've ended up with a bunch of cast-off macs - several IIe's, a IIci, Quadra 610, Performa 575, Powerbook 160 , Powerbook 180c, and a Powermac 6100/66. I used to have a couple IIsi's and a IIfx, but they were "accidentally" tossed when they got in the way of some overzealous spring cleaning by a person who shall remain nameless. I've got the IIci and the 6100 on my network at home to use all of the expensive (well, when I bought them) SCSI peripherals that my iMac can't connect to. Here's my question for you vintage Mac people - The IIci I have originally had A/UX on it (I got it from NASA), but the HD was bad when I was given the machine. I'd like to try to run A/UX just for the heck of it, but it seems to be a pretty elusive piece of software. Not public domain, it seems? Apple doesn't seem to want to remember it ever existed.

Ok, I may have just answered my own question...a friend of mine says he has some hard drives that he pulled out of a couple Apple Workgroup Servers that were running A/UX. Can I use one of these in my IIci?

Thanks 5300. Those drives my friend gave me appear to be bad anyway - one has definitely had massive internal damage by the sound of things (grinding noises)

I don't think it's worth it trying to run an OS illegally, so I just tried Debian on the IIci - it runs VERY SLOW. I think I'll try running Linux on a faster machine, and leave my poor IIci alone with its OS 7.5.3