Aha so that answers my question about why they haven't at least switched to USB thumb drives for their sneakernet. These aren't PCs. Probably minicomputers such as a TI-990 or similar. They don't have USB ports.
That said the 3.5" drives were actually electrically compatible with the double density 8" SA-800 drives.
That said the 3.5" drives were actually electrically compatible with the double density 8" SA-800 drives.