All of the bolts are there on TT they did not back out. I took them out and put lock tight on them before the install.Also all the bolts are on the ring gear, i don't know what happened. If you look at the pics below a bolt broke off inside the housing.
How many times have those bearing cap bolts been reused?? Looks like one of those bolts gave way. If they have been taken out and reused a few times they could have been stretched.