Is It Posi? (8 3/4)

so about these spacers my differential is clamped to stands axles are out so then out comes OPEN 3rd mem as assbly now spacers are attached to ??and come out how??is there an article of this swap and setup?? thanx for the help just dont want things that shoudnt fall out or have to chisle things apart w/out knowing THE things to chisel