The pressure load from the pump has a tendency on working hard in the slots of the case half where the pump is fitted. With time this can cause leaks and case failure.
The case protector drops in to the case where the pump normally would and then the pump on top of it. This helps spread the load of the pump pressure over a greater area decreasing the usual points of stress on the case.
This case protector is compatible for the NP236, NP246, NP261 and NP263 transfer case or gearbox, as it is known in other parts of the world.
Remember to inspect the case half, pump and other parts thoroughly and to use the recommended fluids in all your projects.