Today my rear differential decided to "come unbolted " while driving through town to work. Now the diff is pushed down into my exhaust causing them to rub. anyone familiar with this that can tell me what would cause this to happen and if can tell me if I'm missing a spacer and would it be better to go with longer bolts ? Seems like Two bolts underneath disappeared and the two in the back popped out of place . Verify or correct me please