Kubota RTV1100 door glass

[drmkchr]

I've got a Kubota RTV1100 Realtree camo model. It came with a sliding window on the drivers door. I'd really like to replace the window in the passenger door with one that has the sliding window in it. The dogs have really scratched the existing solid glass window up and they would like a window to stick their heads out of.
Where can I purchase one?
I've contacted a couple of dealers and they both had no clue. Why is it so difficult to find.
Help anyone!!!!!