Wilwood’s OEM Replacement Racing Rotors for Modifieds: Wilwood Engineering is proud to introduce our OEM-Replacement line of racing rotors to the industry. These rotors were designed utilizing the latest developments in iron formulation technology using our proprietary blend ferrous alloy to bring you the strongest, lightweight, most dependable rotor available in the market place. The rotors are new castings, not reworked parts and our tolerances are held to the high standards you have come to expect from Wilwood Engineering. GM Metric type rotors come standard with races and 5/8” coarse wheel studs installed in the 5 on 5 bolt pattern. Standard rotors come with 2.14" long studs. LS rotors come with an increased length, 3.14" long wheel stud to simplify wheel spacing. The GM Metric rotor is 10.50” diameter by 1.00” thick and fits the 1979-1988 GM spindles with OE 10.50" rotors.