Sure grip questions

I think I've answered most of these questions after more research. Looking at pics, the posi in the Magnum actually seems to be an Auburn-style lsd. Idk if that's OEM or not. And from what else I've read, those are the cone/clutch mechanisms which are NOT rebuildable. Also, there is a carrier split at 2.56+ for the trac lok (and Auburn) according to most vendor sites. I guess the one I visited was misinformed... maybe?