For those people needing narrow SCSI disks to keep old hardware going, I happened to see this page the other day: <http://www.redrocktech.com/products/scsi-drives>
They appear to be newer SSD and spinning rust packaged in a 3.5" form factor with a narrow SCSI interface. I have no idea as to the quality or cost, although I would expect the per-unit cost to be higher than modern drives due to (lack of) economies of scale. Devin