Front insulator bolt. Left.2006-10. Right.2006-10. A threaded rod with a drive head (such as hex, 12 point, torx, etc) on one end used to secure the Differential Housing Mount to it's Mounting point. A threaded rod with a drive head (such as hex, 12 point, torx, etc) on one end used to secure the Differential Housing to it's Mounting point. Bushing. Housing.