The nut in the center with 6 slots machined in it needs to come off. Then there will be another right behind it that needs to come off. You can use a punch and hammer or you could get the correct tool at a Napa or some sort of parts store that knows bigger trucks. Once those are off then the drum and hub should pull off.
Be careful, they are heavy. When or if you want better brakes I am making a disc brake conversion that also switches over to a vacuum boosted master that mounts in the original location!
Good luck and you may also try posting questions in the Bigbolts section.
