Yeah, physically, you might need something to poke the disk in far enough through the case, but I was asking more about if the drive actually could operate. There are some Macs that must be able to use both, i.e. some Centris 660AVs had one some had the other, and apparently identical logic boards.
From experience, I have verified an auto-inject drive as NOT working in a Power Mac 5500. I guess I've always kind of wondered about this compatibility, where the cutoffs are, etc.