Differential oil level SP36

[williamcharrison]

Just completed a lube job on my 90 SP36 and noted only one place
on the differential having what looked like an inspection plug.
It appears to be a slotted end shaft with a locknut on it. Is this
where the oil level is checked? If so, what should the level be
and is there any guidelines for how far the slotted shaft should be
screwed back in?

Chuck Harrison
90 SP36
Akron, Ohio