This makes my life easy.  No wrenches, turning the wheels for access, just pump and done.

If you pack your Birfields properly and the knuckle no need for this.

What can I say?  I'm brainless and lazy.  Id'e rather pack the crap out of these and never worry about not having enough grease and I grease these so often I wouldn't know if the seal was blown.  As is, I've got 330k and have never needed to rebuild the knuckles.  If I did, a grease mess would be the least of my problems.  To me it's cheaper than replacing worn drivetrain parts.

^ I was wondering about that... How much to pack into my knuckles..

I've got an 83 complete axle waiting for me, I just need to take it apart, and replace a few seals I think... But it's good to know that I don't need to pack it that full of grease! Kind of difficult to justify packing it with 3 tubes of grease while most of it is just going to sit in there taking up space... I think I heard someone say that it's the theory that if it's full of grease, there's no room for water, but if it's sealed, how the heck is water gonna get in there?

I only posted the grease pressure relief fittings to solve the over greasing potential problem, but if only a handful of grease is required, then my suggestion is null..

Even if you pack the birfield and pack the knuckle, over time it will pack against the inside of the knuckle and move away from the birfield anyway