I would contact Doctordiff for the correct axle seals for your rear.If the lube is getting past your sealed axle bearing then it has already washed the lube off the bearing.
The level could be up to the top of the housing and if your seals are good and the vent is in good working order the lube should never get past the seal.
Gus


64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60