When you disassembled it originally was the
oil leaking from the inner seal which rides on the axle shaft or was it coming from the outer diameter of the seal IE: at the parting line for the axle housing flange and bearing retainer????
Inspect the OD of the seal (black band) if it's ok reassemble carefully with a little sealer. One last thing. If the lubricant level is overfilled in the rear end itself it will lend itself to the potential of leaks. Typically lubricant is sloshed into the tubes and it migrates to the bearings but if you over fill it it will have the
oil level above the bottom of the outer seal.
Rick