Rear Axle Assembly - Professional Quick Change - 10 in Ring Gear - 4.12 Ratio Standard - Magnesium Center - Each. **NOTE: ALL SATURDAY NIGHT REARS COME WITH 100% MAG CENTER/BELLS O-RINGED REAR COVER W/ HEAVY DUTY BEARING BREATHER ASSY. ALUM. SPOOL INSP. PLUG / FILL PLUG CORRECT LENGTH CENTER HARDWARE BELL TO TUBE HDW.