I heard a story of someone trying to remove a stuck kingpin with the sledgehammer method... tried so hard they noticeably bent the axle, seriously affecting camber on that side.
the hydraulic press is the safer option if you can remove the whole axle.

If you can't remove the axle then a hydraulic kingpin press is an option.
http://www.ntxtools.com/network-tool-warehouse/OTC-4240.html
And the non hydraulic version
http://buy1.snapon.com/catalog/item...2&store=snapon-store&dir=catalog

Grigg

•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-