1977 Mercury Grand Marquis Differential Carrier RWD - Yukon Dura Grip - Ford 9 in. Rear - 28 Spline - Limited Slip - 2 Spring Smooth Setup - Requires Longer Trac-Loc Bolts - 1.78 in. Bearing Journals - Rear guaranteed to replace your current 1977 Mercury Grand Marquis Differential Carrier RWD - Yukon Dura Grip - Ford 9 in. Rear - 28 Spline - Limited Slip - 2 Spring Smooth Setup - Requires Longer Trac-Loc Bolts - 1.78 in. Bearing Journals - Rear. 1977 Mercury Grand Marquis Differential Carrier comes new OEM 1977 Mercury Grand Marquis Differential Carrier aftermarket new 1977 Mercury Grand Marquis Differential Carrier of remanufactured 1977 Mercury Grand Marquis Differential Carrier RWD - Yukon Dura Grip - Ford 9 in. Rear - 28 Spline - Limited Slip - 2 Spring Smooth Setup - Requires Longer Trac-Loc Bolts - 1.78 in. Bearing Journals - Rear.