The original version of 68000 Cromix for the DPU was actually just Cromix (not plus), CRO-D versions 20.05 through 20.65
AFAIK Cromix+ started with version 30.51 and went up through 172XXU (they changed the numbering system to confuse us), although after a certain release it required an XPU or XXU processor and no longer worked with the DPU.
Whether or not a given version would work for you depends on your hardware configuration; certain upgrades required board mods, ROM upgrades, etc.
Then there's the issue of creating disks from images; the most reliable tends to be using 8" images on a 1.2MB HD floppy drive.
I don't have access at the moment but I'm pretty sure I have a DPU available.