4 0 Rockwell RS13120 Rear Differential for a Rockwell RS-13-120 $600 USD Good used Rockwell RS-13-120 rear, rear differential assembly. 3.31 ratio. 90 day guarantee for swap or refund ConditionUsedRear End3.31 ratioFits To Make(s)ROCKWELLFits To Model(s)RS-13-120Stock NumberRyd RS-13-120/3.31/ MLS Number11710275CategoryDifferentials, Rear Last Updated7/30/2025 LocationFitchburg, MA, US Sold ByRydemore Heavy Duty Truck Parts (888) 519-___ SHOWNUMBERCall Seller Email Seller Save More Info