4wd front end

[86c20]

ok i have my first 4x4 its a k30 85 it has king pins i think?? anyway i get a bad shake some times when breaking hard will through the truck all over the place. she will do it some times at low speed 30 mph and not allways under hard breaking either. front end seems tight for the most part but it is getting bad. i read some where about a king pin death shake??? i dont know if that is what is going on or if it is a wheel bearing going. i just need to fix it but dont know where to start.
thanks guys, mike