Nissan B10 Datsun Sunny Type A Genuine Transmission Shift Part Included Clutch Gear Museum? Exhibit? Contemporary Object

I came out of the warehouse at my parents' house.

This is a part that my grandfather and father took as a spare for their B10 Datsun Sunny.

The plate that says clutch and mission case have been stripped of their casing so that you can see the internal structure. I think it's probably from a museum or an exhibit. If you turn the main shaft by hand, it will turn normally, so I think it was removed from the actual car. The exterior is painted green without the skin.