This is a replacement seal for the Selector Shaft Sensor located in the top of the front half of GM NP261HD, NP263HD, NP261XHD and NP263XHD transfer cases. It also fits the Detent Plug located in the bottom of the front half of the same transfer case models. The same O-ring seal is used in both locations, you will need to purchase two units to replace both seals in a single transfer case.
