Ball joints...

[JMBT]

I am guessing you are talking about your kingpins. On any KW or Pete I have done the thing on the bottom is just a dust cap. You are correct, you will unscrew it, but the kingpin will not fall out. Once you have removed everything connected to the spindle and the dust caps on the top and bottom of the kingpin. There will be one or two bolts, depending on the axle model, that run perpendicular to the pin, look for them near your turn stop bolt, remove those. If you are really lucky and the bushings aren’t beat to hell, you can wiggle the spindle a bit and the pin will slide out the bottom. However usually, you have to get a drift and beat the living shi#t out of it. Support the spindle and put a 6x6 block or a jack stand under the axle eye so each blow you strike isn’t wasted in axle flex. I have seen them go both ways, slide out easy breezy, or pound until you think you are gonna destroy something and then she falls out. Once the kingpin is out remove the thrust bearing, under the axle eye, there may also be some shims, then you can remove the spindle, and start pounding or pressing out the bushings from the spindle eyelets.
As for replacements, I use the Kyser Kwik set. The kit will come with, the king pins, shims, thrust bearings, and instead of bushings, a stainless steel coil that you can slide into the eyelets on the spindle by hand, no pressing or pounding. Since it is a coil it allows grease to actually lubricate the lower bushing when you grease the truck with the front end on the ground. Eliminating the need for lifting the front end off the ground for proper greasing of the lower OEM style bushing.
I just did my brother’s 99 W9, the pins took a little pursueding with a dead blow hammer, but nothing like the “stepped” kingpins in a Volvo front end. Look on you tube and you can find some vids of guys swapping kingpins on KW’s.