bigger than a chapstick cap

[Nobluecircles]

Wondering what this little oddity is. Seems to have a slight protrusion on the top and bottom of lid.

Upon lightly cleaning the inside area, cough syrup color dark red was on rag. A cap for oil or transmission fuel dip stick?

 

[Jublain]

Maybe part of a lantern? I would say the little slit is where the wick come out. Just a guess tho...

 

[cudamark]

A transmission dip stick collar looks like a good guess to me. That center "slot" looking area would be where the flat stick passed through the cap and then was curved to form a handle. The purpose of the cap was to prevent foreign material from going down the tube and into the transmission. Some engines used the same design but were a lot smaller as they didn't use that point for filling, just measuring.

 

[Back-of-the-boat]

I have also seen a buss fuse that has copper end like that.