I have removed lots of king pins and here is how I have had the best luck in doing so.
1. Remove all the brake assemble, tie rod from the steering knuckle, and anything else from the steering arm. Use a sharp small chisel or something to remove the soft plugs on the top and bottom to expose the king pin.{make sure the vehicle is supported good} Remove the tapered bolt that is holding the king pin in. Find a short piece of shafting slightly smaller in diameter than the king pin. If you have a jack that screws to raise and lower it is best, but a heavy hyd. jack will do, jack the vehicle up to where it just raises up off the stands you had supporting it. Use a heavy sledge hammer and hit down on the axle just inside of the steering arm. [what you are trying to do is use the vehicles weight to help push the king pin out] If this won't jar the king pin loose try squirting some penetrating oil in the hole where the tapered bolt was. I have had to heat the axle up red hot some times to get it to break loose. The reason I mentioned a screw jack is to get the support as solid as you can, there is a small amount of give in a hyd. jack. If heat doesn't seem to get it to break loose then heat it again and while it is really hot squirt it with a stream of water from a garden hose.
I have had some real times getting them to break loose and as the last resort, remove the axle and take it to a hyd. press and press it out.
