If you can't easily remove the old kingpins then best to remove the whole axle and have it pressed apart. (or use a portable kingpin press in place if you have one) Swinging a big sledge hammer trying to remove kingpins can bend the axle.

If the new pins fit nice and snug in the axle beam there is generally no machine work necessary, if not then you're looking at oversize kingpins and the axle needs to be reamed or honed also. They should be a snug fit, should not wobble at all, and should not fall out. Should need a firm push of you palm or a rubber mallet to get a new kingpin in or out of the axle.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-