Window

Its more than likely a Hehr window made in Elkhart, try them

Most RV owners manuals are not very helpful and just generic stuff. If you need owners manuals for the different appliances, you might be able to find them at Bryant RV Service. That site is owned by a member of our forums , Chris Bryant, who generously makes them available to us and the rest of the RV community. :)
If you are looking for service manuals, click here.

As far as the window goes, I would go to a local auto glass shop and see what they can do. They most likely can cut you the proper size and install it also. If you need a frame for it, they can probably find it or make it up for you.
Another source for a window would be one of the largest RV surplus outfits around Bontragers RV Surplus.
I have been there several times and am amazed every time I go with what they have for sale. I feel almost like a kid in a candy store! :B
Barney

There really aren't any owners manuals that I have ever seen. The dealers give you literature about the components. Any user's manual is not like a car which tells you how things work, where to find things, etc