Any idea what this goes to?

[Bluesman1148]

Just returned from a great trip to Colorado and found this on my trailer when I got home.  Looks like some sort of a rubber plug that threads into something, but I can’t tell off hand.  Anyone have any insight?

 

[Steelslinger]

I can't say that I've seen that any where on my machine.

I'd check around the engine and trans/diff. Looks to me to be some sort of threaded hole protector.

 

[norman]

More than likely one of the plugs from the pvc liner 

 

[Bluesman1148]

What is the PVC Liner?