That leaves me with the other MicroVAX that reports the disk drive as an RA82 - but it clearly isn't!
The machine is a MicroVAX 3300 in a BA215 cabinet with a KA640 CPU.
A "SHOW DEVICES" command from the ">>>" prompt identifies a UQSSP Disk controller at 772150 and a DUA0 disk which reports as an RA82. But this physically looks like a conventional disk drive - and not something the size of a small car!
Is the disk drive in question mounted internal to the BA215 cabinet? What type of cables are attached to the drive?
The M7624 KA640 CPU has an on-board DSSI controller, however if the drive was attached to that controller it would show up as a DIAx drive, note a DUAx drive.
If the controller shows up at 772150 with a DUA0 disk then it is an MSCP controller of some sort. If you pull the front covers off of the BA215 card slots, what boards are installed in addition to the M7624 KA640 CPU and M7621 / M7622 MS650 memory boards?
It is possible there might be an M7769 KFQSA DSSI controller installed, although that wouldn't make much sense as the M7624 KA640 CPU has the on-board DSSI controller.
Or maybe an M7164 / M7165 KDA50 SDI controller board pair.
Or maybe an M7555 RQDX3 MFM controller.
If it isn't one of those, it is most likely a 3rd party MSCP SCSI controller.
From a quick look at the installed boards and cables attached to the internal drive should be pretty easy to determine what the situation is.