Pinion Seal Diff Opening

[Blue15]

Total newb question, but changing the pinion seal on my 2015 1500 because it was seeping. Got the seal off and there is this small opening looking into the differential. Is there where the fluid comes in? Seal was PITA to pop off so wanna make sure I didn't break anything. Nothing goes in here like a lock ring or anything right? The new seal doesn't seem to have a specific side or anything, so just assuming when the fluid is at the right level, this is kinda the passthrough from the back of the diff. Thanks for the help!

 

[silveradosid]

it is actually a drain back into the diff.  it is to keep a certain amount of oil in the bearing at all times , but not to much

[Blue15]

@silveradosid Perfect! Thank you! I have a knack for breaking things when I take them apart so this puts me at ease.