Last night I went to top off my front diff because of a leak I described here
I was able to pump in about 3/4 of a quart before full and then noticed that there was a vent hose hanging near the axle tube.
Come to find out this is the vent hose for the front differential and with it disconnected there is a 3/8" hole on the tube open to the world.

I reconnected it and put the fill plug back in place.
I'll check it again in a couple of weeks but this is probably the main source of the leak.
I'm still planning on doing the axle shaft bearings, tube seals and pinion seal described here


CV/Axle shaft flange connection on the right


close up of reconnected vent

 

That little plastic nipple just pushes into the hole in the axle housing, held in by friction. If it's leaking, you can try wrapping some teflon tape around it before pushing it in.

Several years ago, I was advised to replace the atf in the front axle with gear lube. Terrible idea. The gear lube got a lot hotter than the atf as it was so much thicker, and expanded out the vent hose; it pushed its way all the way up the rubber hose to where it ended in the frame, and leaked all over the frame. I have to keep replacing the lost gear lube with atf, until it stops.