I believe the book calls for 90w every 1000 miles on the '60's DANA axles. That was probably probably fine for a new axle, but I have always ended up pumping grease in the hole. After a while that gear lube just runs out and all over everything.
On our NAPCO axles, there's a slotted plug on back of ball that you remove, then grease the zerk until grease comes out of the plug hole.
