Any tips; persistent axle seal leak

[Vikingdude]

I'm at my wits end with my front differential. I have a 1997 Yukon 1500 4x4, and when I first got it both front axle seals leaked. I changed them both with National brand seals from the parts store and resealed the axle tube, the passenger side was good after that. Drivers continued to leak. I changed the drivers side with the genuine GM seal from the dealer after that and used a green scotchbrite pad to gently clean the cv stub. Still leaked. Took it to a mechanic, and he changed the seal a third time. Still leaked. Next I changed out the vent in the diff housing and replaced the vent hose, but it still leaks. It drips quite a but and my parking spot is an embarrassment. It's definitely coming from the drivers side axle seal. Is there something I'm totally missing? Should I try a new stub? Should a get a rebuilt axle? I've read over the FSM and some of the TSBs but nothing seems to be the smoking gun I'm looking for.

 

[termite]

I'm assuming you've checked the stub shaft for a groove worn in where the seal rides? Takes a bit of care reinserting the stub to prevent damaging the seal on assembly.

 

[Schurkey]

Wobbly bearings? If the shaft the seal rides on isn't stable, the seal lips lose contact with the shaft. That's a guaranteed leak.

Rusted/pitted/dented shaft?

Cracked casting that the seal pops into?

Overfilled fluid level?

 

[Vikingdude]

I haven't thought of bearing wobble. Good one!

Stub shaft seemed clean both times I had it out, nothing I could catch a fingernail on. I've thought about just replacing it anyways.

As for fluid level, I've always run the factory recommended 1cm below the fill port. Can you safely get away with less?