8 3/4 rear end confusion

I pulled the diff and was able to find the second button at the bottom of the casing. The button honestly looks completely intact so idk what that material is from. It does seem like there are some shavings throughout the gears. Don’t know if I can just hot tank the entire thing or if I have to change out the bearings like you said bluNBlu. I’ll have to do a bit more digging to see if there was any damage. Also, there was absolutely no fluid in the dif housing…not a drop. Maybe that explains the shavings. Might have to do the gears as well but again, this is all new to me. Will continue to update with more info, thanks guys.