For SCO, the release numbers were different (at least at the end), Release 2.3.2 was 286,
2.3.4 was 386. Earlier (2.2 series) I'm not as sure of, my disks specify "SCO
XENIX 386" on the 386 specific bits, and they just say "SCO XENIX" on the
utility & games volumes (likely common). Minix 1.1+ can be had from
www.minix3.org/previous-versions/index.html, and Coherent is available online if you poke
around, too, but I think it might be the 386+ only V4.10.