The picture is very helpful. I really appreciate you uploading it. I change my bevel box oil at every engine/trans oil change, which is about every 3,000 miles (I'm stubbornly old school with oil changes). I've had the plug out many times but this time there's nothing left of it. I won't bore you with a description of what happened when trying to get it out because I wrote a long, boring, detailed post about that seperately. Long story short, the plug came out fine. When reinstalling it, it just started spinning when barely finger tight. Virtually no torque. Nothing would get it out. I modified a tool to get a really good grip on it so I could pull and turn at the same time. No luck. I tried heating it. No luck. Finally, I drilled just as deep as the plug head starting with very small drills and working up until the plug head dropped off. To my surprise, there was no bolt to be seen in the hole. I can see right through to the ring gear. I'm thinking, "Un Oh!" Wheres the rest of the bolt and the magnet? Did any metal get in the bevel box? (I still don't know.)
So here's two questions that I hope someone can answer:
1) Is the bolt hollow? I don't remember it being hollow. But as I said above, once the plug head was drilled off, I can see all the way through to the ring gear.
2) How is the magnet installed? I just never inspected it in the past so I can't remember. Is it inserted into a hollow plug bolt?
Needless to say, what should have been a minor problem has turned into a major one. And if metal got into the bevel box, I may have to buy a new bevel box for something like $2,300 and it may take a long time to get one. There's used ones on eBay but I wouldn't know what I'm getting if I go that route.
