2012 Meritor/Rockwell RR23-160, Truck Tractor, Rear Rears (Tandem Rear or Single), Fits to: Western Star 4900 SA, (Used) 2012 Western Star 4900 SA, COMPLETE REAR DIFFERENTIAL GEARS ONLY- Part Number: 33063A7051G3.91, Serial Number: FOR01693785, Make: Meritor/Rockwell, Model: RR23160NCN2890 391, Ratio: 3.91, Capacity: 23,000 Lbs, Hub Bolts: 10, Brake Type: Drum, For more information about this item, give us a call. We ship Worldwide! (CRG HEAVY TRUCK PARTS) 929 W PULASKI HWY, ELKTON, MD 21921, Ratio 3.91, Serial# FOR01693785, Casting# FOR01693785 5KJJALDR8CPBN4842