Go to Tech Tips and read KOOLKAR'S King Pin removal, great tip, here's how I did it...
My last major project was 'encouraging out' the old king pins. Koolkar suggested using the weight of the vehicle and a generous soaking w/ PB Blaster to achieve success. In my case it worked like a charm.
The truck is lifted and properly supported while you remove the backing plate and coat-hanger it off to the side. I then created a stable vertical support for my brass drift by drilling a common hole into a stack of 10"X10", 2X12 board scraps then securing the stack together with 3 " wood screws. This created a stable vertical support for my 6" brass drift. Upon removal of the king pin end caps I then lowered the king pin onto my home-made brass drift assembly.
The goal is just to get the stubborn king pin started so only 1-2" of drop is allowed before 2 jack stands await the front I beam for safety. I would come around and give a dozen good blows to the outside of the vertical king pin assembly with a five lb. sledge and a squirt of PB then go back to listening to Public Broadcasting Saturday AM and then come back after another half hour or so. Once I noticed a 1-2 mm drop all thoughts of jerking the whole axle and taking it someplace to have the K-pin pressed out melted away.
As with most things in life and with our old trucks, good patience is rewarded in the end with success.

~ Cosmo
1949 Chevy Half Ton
Rocinante, like Don Quixote, he is awkward, past his prime, and engaged in a task beyond his capacities.
"...my good horse Rocinante, mine eternal and inseparable companion in all my journeys and courses." ...Don Quixote, Cervantes
"If you come to a fork in the road, take it."...Yogi Berra
"Rudeness is the weak man's imitation of strength." ...Eric Hoffer