I'm not sure if it is only "SCSI-1" that will work in the SE/30. I had this IBM DGHS drive internal to my SE/30 in the past and it worked perfectly. (I only moved it to an HD20 enclosure to reduce heat inside my SE/30.) But as you can see in my photo, this is an "Ultra" SCSI drive, originally used in servers. And if this SCSI wiki is to be taken at face value, then Ultra Narrow SCSI = "SCSI-3 SPI". So I guess that would mean that so long as a "Narrow" SCSI drive has a 50-pin connector, is terminated correctly, and comes in a 3.5" low profile form factor, it will work internal to an SE/30 even if it is SCSI-1 or SCSI-2 or SCSI-3.