it's not a big problem, but on my 1925 pickup it's always leaking at the U-joint. I already use a "Universal joint shim".
Can it really be dry there ?
If it is not leaking grease it is out of grease and you need to fill the U-joint ball. Sorry.
If it's leaking oil, it's coming out of the engine. There are a few possibilities. The fourth or rear main ball cap bearing could be loose, passing oil. The gasket under the ball cap may be leaking. The transmission output shaft/driven plate could be missing the plug behind the main shaft bushing. All of these require major surgery to correct. If there are no other alarming symptoms or noises, keep the u joint housing packed with grease and drive it. Oil doesn't cost that much.
And if you stop the oil/grease mix leaking from the u-joint by greasing it up good as it should be, then sometimes the oil that leaks from a fourth main with worn babbitt finds its way along the driveshaft tube into the rear axle, so keep on checking the engine oil before every start of the engine and check the level in the rear end from time to time.. Too much and too thin oil in the rear end tends to leak out at the emergency brakes.
And check so there isn't any gasket between the cup that holds the u-joint ball and the fourth main flange. There should only be one gasket there = between the engine and the fourth main flange.
Thanks for you all !!
Great tips. I will check all of them !