The R1 Concepts drilled and slotted black rear left brake rotor for 1998-2012 Sterling Acterra with hydro brakes is listed as the replacement rotor for the rear left position on those model years. The source explicitly ties this drilled-and-slotted black rotor to Acterra vehicles with hydro brakes; confirm fitment details and brake type before ordering.
R1 98-12 Sterling Acterra (Hydro Brakes) Rear Left Drilled & Slotted Black Brake Rotor