1978 Mack 11KHA, Truck Trailer, Front Rears (Tandem Front), Fits to: Mack RD685S, (Used) 1978 Mack RD685S, FRONT DIFFERENTIAL GEARS ONLY- Part Number: 64KH595P4, Serial Number: 5236DP, Make: Make, Model: 11KHA, Ratio: 4.17, Capacity: 21,000Lbs, 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 4.17, Serial# 5236DP, Casting# 5236DP RD685S3685