The SOP Halibrand/ Winters Racing Billet Aluminum Quick Change Rear End Detroit Locker Differential interchange #5114-01 is a high-quality rear differential designed for 10", 11 and12 bolt applications such as Frankland, Franklin, and other stock car products. It is interchangeable with P/N QC431A and fits various brands like Winters, Richmond, and Tiger. This locker includes the necessary components for easy installation, making it a convenient and reliable choice for car enthusiasts looking to upgrade their drivetrain system. Some early Halibrand applications may require minor machining for clearance. Buyer responsible for making sure this unit will fit their application. 31 spline.