2017 Detroit RT40-4N, Truck Tractor, Front Rears (Tandem Front), Fits to: Western Star 5700, (Used) 2017 Western Star 5700, FRONT DIFFERENTIAL GEARS ONLY- Part Number: C11-00042-390, Serial Number: 771AAC-A170632H, Make: Detroit, Model: RT40-4N, Ratio: 3.08, Capacity: 20,000 Lbs, For more information about this item, give us a call. We ship Worldwide! (CRG HEAVY TRUCK PARTS) 929 W PULASKI HWY ELKTON, MD 21921 - Differential Make (Rear): Detroit - Differential Model (Rear): RT40-4N, Ratio 3.08, Serial# 771AAC-A170632H, Casting# 771AAC-A170632H 5KJJBLDR2HLHX6381