The "HD 20" & "HD-20SC" are often confused due to the similar labeling. The SC refers to SCSI, while the earlier HD 20 was floppy-based. The HD-20SC was one of 4 original HD-SC drives offered by Apple. They came in 20MB, 40MB, 80MB & 160MB models. All of the cases were identical except for front labeling, they could contain 3.5" or 5.25" drives and all could be upgraded at anytime, with smaller, cooler and larger capacity drives. I'm not surprised yours has been altered. Only the 20SC seems to have come in both beige and Platinum, presumably to match the earlier Mac Plus which was beige for several more months following the HD-20SC release.