#3. Bracket bolt. PartQualifier: #3. A threaded rod with a drive head (such as hex, 12 point, torx, etc) on one end used to secure the AWD Coupling Unit to its Mounting surface. 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. A/C Compressor Bolt. Alternator Bracket Bolt. Belt Tensioner Bolt. Power Steering Pump Mounting Bolt.