OTC 1981 2 1/2 Pinion Locknut SocketOTC Tools OTC 1981 2 1 2 Pinion Locknut Socket. Socket has a 3 4" square drive opening, permitting the use of an extension and torque wrench to tighten locknut as required. Locknut removal and installation is simple, even when wide rim wheels are involved, since a long extension may be attached to the socket to provide the necessary clearance. Socket is made of high strength steel; openings resists round out. Eliminates modifying standard socket to