Front Diff Leak

I found a leak on the front diff passenger side, it appears to be leaking from where the axle shaft goes into the diff. Seems like a strange place to leak, is there a seal where the shaft goes into the differential? Or is it most likely just the diff seal itself?

I've replaced a few cv axles before, but I don't recall any seals being right there. Any input or ideas?

Any part numbers for these seals? (99 OBS 4EAT)