It appears that the case will be OUT of the axle housing.
The 2 types of SG differentials were the Dana power Lock and the Auburn. Each is unique. The Dana is the preferred because it is easily rebuildable.
Nevertheless... the quickest way to determine if it is a SG diff: The OPEN/One legger unit has large openings where the spider gears are visible. You can fit your fingers in and easily touch the center pin as well. The SG diffs have much smaller openings.