the conversion company is out of biz. eBay seller wouldn't write back. so i ended up making one out of thin plywood that's pretty rough but should work, at least for a little while.

 

The conversion company probably didn't make the window frame. It came as an assembly. With the company belly up, there may be no way to find out who made the window assembly. RV suppliers can sell you a window. One might be available, but I wouldn't hold my breath as body styles are different now and that particular assembly may be unavalable.