1982 Chevrolet C20 with Fixed Orifice; Except Notched; Position: Rear;. 1983 Chevrolet C20 Submodel: Custom; with Fixed Orifice; Except Notched; Position: Rear;. 1983 Chevrolet C20 Submodel: Silverado; with Fixed Orifice; Except Notched; Position: Rear;.