TSB: REVISION NOTICE February 8, 2019 Rev1: ? The Warranty Information section has been updated. Any previous printed versions of this bulletin should be discarded. Some 2016 ? 2019 model year 4Runner 4WD vehicles may exhibit a cyclical groaning/grinding noise from the front differential in 2WD that is not present during 4WD operation. Follow the Repair Procedure in this bulletin to address this condition.