View 0 Photos View 0 Videos 2017 Eaton S21-170D Rear Differential for a Peterbilt 337 $2,420 USD (USED) Eaton S21-170D Ratio: 4.56 Side Gear Splines: 46 W/ Locker: YES Cast#: 515667 ConditionUsedFits To Make(s)PeterbiltFits To Model(s)337Stock Number25878395 MLS Number13882075CategoryDifferentials, Rear Last Updated10/22/2025 LocationSpencer, IA, US Sold ByVander Haag's Inc. (855) 370-___ SHOWNUMBERCall Seller Email Seller Save More Info