Cut to the chase and apply some gentle heat to loosen up the hard grease.
Also, make sure the bushings were installed with the hole lined up with the grease fitting to allow the grease to get to the kingpin.
I recently pulled a '54 3600 axle out of a truck at the junkyard that had a recent brake and kingpin job. I couldn't get the fittings to take any grease and after removal of the fittings I dicovered the jacka$$ that did the kingpin job didn't line up the bushing holes with the grease fittings!


Steve

'49 3800
'52 3600
'57 3100