The original CD-ROM drive for the IIvx and IIvi was a CD-300-ish (from memory) and was definitely a tray loader. The IIvx/vi was the first Mac to have a CD drive as an official internal upgrade, and is thus noteworthy. If your IIvx has a caddy drive, it is a hack using an older Apple or third party CD drive. Any CD will work in the drive bay, given the correct drivers. However, you can't use a tray load drive unless it lines up physically with the bezel. Unless you remove the bezel.
Has anyone out there checked how well different Apple CD-ROM tray load drives align in different cases? SCSI and ATAPI? I doubt it but it is a useful project. All you need is lots of drives and a metal engineering ruler.
