This is the basic seal kit for the NV146. This is recommended for vehicles with higher mileage and showing signs of leakage. This is also recommended for any rebuild that is over the 80K mile mark. The input seal only needs to be replaced if the transfer case is being removed from the vehicle. Recommend coating the outer surface of the seal with a VERY thin layer of RTV if the case is damaged or gauged when removing the OEM seals.