Deere 265 Tiller belt

[Zick]

I am borrowing my father-in-laws John Deere 265 w/ the 30" mech tiller and found it needs a new belt.
I went onto JD's website and found two different belt numbers for the rear secondary belt. M112230 & M137547
Now since there is only one belt in the rear that I can tell, does anyone know which one is the correct one?

Thanks