3 0 Mack X107 Transmission for a 1981 Mack R686ST Contact for price (Used) 1980 Mack (MT), TRANSMISSON ASSEMBLY- Model: X107 Serial Number: 0V9771, Part Number: 284KB5175, Engine: Mack EM6, Reference images for condition. For more information about this... ConditionUsedEngine ModelMack EM6Fits To Make(s)MackFits To Model(s)R686STWill Fit Year(s)1981Part Number284KB5175Stock NumberP-60340 MLS Number12337632CategoryTransmissions Last Updated11/11/2025 LocationElkton, MD, US Sold ByCRG Heavy Truck Parts (844) 402-___ SHOWNUMBERCall Seller Email Seller Save More Info