Of course, if I counted right, it's got a DB-25, it's oriented for the 500, and it definitely claims to be a SCSI card.
This could mean the data on it in the hardware book is a little off, or it could be a different model from the same manufacturer, or at least someone using the same casework. Or I could be all turned around from squinting at it so long.
IMHO, that sort of 'flat and adapted from a vertical A1000 expansion' casework dates it as a relatively early product, maybe.