Differential oil blowing out

This housing was acquired by a Mopar friend of mine. It has not been modified. I believe some of the earlier designs had the vent there, then relocated. I know on the B-Body I owned, the vent was located farther down on the tube area. As far as the level, the rule of thumb was if it was level with the plug to 1/2" below, you were good. The gear ratio is 3:90-1 with a Gear-Vendors O/D. My plan is to pull the rear housing after the season, plug the current vent, and relocate it further down inn the tube area.