Never in a differential or gearbox.
"Formulated for John Deere corn head and other slow-speed gear cases"
Its called corn head grease because there evidently is this thing you bolt on a combine for corn stalks that needs this type of grease.
I'm sure any grease is better than no grease, but there really is no need to fill a knuckle with lube. I run my GPW the way I describe, and my CCKW the same way. Rzeppa joints packed, bearings packed, thin coat of grease inside the knuckle for rust prevention.
My 66 M35a2 had the front axles packed with grease.... it must of been in there since it rolled off the factory floor.. I had to melt most of it out with a mapp torch.
