I second to this... putting too much grease will hyrolock it and can cause more damage to other parts. just clean it up and grease around 12 pumps. there's no need to keep greasing it if there are no issues.
Two things:
First, pumping the driveshaft full of grease until you see it expand is a BAD thing. You have now just hydro-locked that sucker from moving and are not allowing it to slip in and out. You are transferring that energy that needs to be absorbed by the driveshaft slip yoke right into the transfer case and the rear pinion. You can remove the driveshaft, clean out the slip yoke and properly lubricate the driveshaft by hand (you homely lookin' single fellas should be familiar with how to lube a shaft :jk.
Second: Driving/braking habits can affect the "clunk" you are hearing. Try braking slower and earlier and eliminating some of the body pitching fore and aft and you'll see that the driveshaft clunk is all but gone or minimized.
