how to change bearings

Does anyone know how to change wheel bearings on a 84 k5 blazer? I know how to change the bearings but my k5 came with with a xtra option from factory, auto locking diffs. when I pull off my hub its packed with gears and springs and past that is'nt the castle nut it this huge nut if anyone knows the process to change the bearings plzzz let me know i juss dont wanna mess any thing up thanks...

does anyone know how to change wheel bearing on a k5 that came with a option from the factory "auto locking diff" need help