missing plug identification Carter GTR 250
 

Was out riding this weekend and all of the sudden I could smell a strong oil smell. After inspecting the buggy I found a plug had come loose and is lost. The fluid looks like and smells like gear oil but I’m not certain. The GTR250 parts manual does not show this plug anywhere on the diagrams. I included a pic of the my buggy with the missing plug, a diagram pic that doesn’t show the part and a pic in the maintenance manual showing what the plug looks like. Anyone know if this is a dipstick of some sort or just a plug? What type of fluid is it? Any help would be awesome. Thank you

Ill check on a spare motor i have laying around. but im almost certain its the gearbox fill plug.