Nobody wrote you back, so you're stuck with my advice. I had kind of the same problem on my Irwin
34. The long cabin
windows were factory made, not pre-built and then installed. So there was no replacement. I scootred over to E-Bay and lay in wait for months looking for windows the right size. After about two months, I found some. They were too big, ( good ) so I could cut the cutouts a little bigger and slide them in. If you are just rebuilding the windows and using the existing the existing frames, you'll have to find plexiglass and cut it to shape. Good luck !