Or if you have a zerk "rejuvenator" You could try that, too. Mine is a Lincoln. But zerks are cheap ...
Another thing, if new zerks or the rejuvenator doesn't help ... put your jack under the front axle and jack it up until the weight is off the front axle. Have a helper slowly turn the steering wheel side to side and back again (over and over and over) while you try to apply the grease gun to the king pin bushings.
Oh ... and be sure to safely support the vehicle with wood blocks, jack stands, etc while you are working under it.
Hope you get it sorted.
John