Vorsprung Autowerk B8/B8.5, C7, Billet Rear Differential Carrier InsertsVorsprung Autowerk Billet Differential Inserts: Precision Where It Matters Eliminate unwanted drivetrain movement and enhance rear end stability with Vorsprung Autowerk Billet Differential Inserts. Precision machined from high grade aluminum, these inserts fill the voids in your factory differential bushings, reducing flex and improving power transfer to the wheels. The result is sharper throttle response, improved traction, and a more connected,