Here is the [275] embossing, which has the extra "S" hanging out above the dash in HEMINGRAY-62. Both pieces above are the same mold number 6. On the left is the listed version with RDP, and on the right is an unlisted SB version. The unlisted one on the right also has a more pronounced dot over the "4" in the date code, so it was undoubtedly made after the RDP version, though in the same year (1937). Could this possibly be the year they phased out RDP on this style?

As a side note, the "S" is actually a remnant of "MADE IN U.S.A." which was blotted out. For some reason they left the "S" (or just forgot to blot it out). I have seen other [275]s where the blot out is clearly visible.