The R1 Concepts drilled-and-slotted black brake rotor is listed as a replacement front-right rotor for Workhorse applications. Catalog detail describes it as drilled & slotted and finished in black, intended to serve as a serviceable rotor for front braking assemblies. Fitment is explicit: for Workhorse 500Lb GVW applications from 2006–2012 in the front-right position.
R1 06-12 Workhorse 500Lb Gvw) Front Right Drilled & Slotted Black Brake Rotor