Some 2016-2019 Toyota 4Runner 4WD vehicles may exhibit a cyclical groaning/grinding noise from the front differential in 2WD that is not present in 4WD operation.
If the condition is confirmed, remove the front differential and install the new/revised front differential. A production change occurred at the Tahara factory starting with VIN JTEBU5JR#K5632980.
The previous front differential part number is 41110-35A91. The new part number is 41110-35A92.