The ST351A/X is one of the few 8bit XT-IDE hard drives from the late 80'.
This is the drive you will use for e.g. the Commodore PC10 and PC20 computers.
It can be configured for 20MB to 40MB and 8bit/16bit IDE.
It has the same performance as the MFM hard drives of the era, but is a 3.5" drive.
Truly a noisy drive with stepper-motor seek and rumbling ball-bearings... Great!