While you may have the twin I beam suspension, its probable that the knuckle is attached to the I beams by ball joints....go look at your truck and see what you have... look at autozones website and see if your trucks has ball joints-you will see the two large nuts holding the knuckle onto the I beam...a king pin will be just a large pin that goes through the I beam which has a notch cut in it to hold it in place....look at these kingpins... http://www.autozone.com/autozone/cat...&parentId=46-0
these king pins has a screw-in cap with a grease fitting to keep junk out...