i have older anderson windows in my home which was built in 1957 i would like to replace them with new anderson windows the problem is i dont want to open up the r.o. if anything i would have to frame down just a little is there a book on older anderson size windows?
Andersen changed their stock sizing since them. I tried to retrofit an older house a couple of years ago. It is not a simple thing to do. You can make RO smaller easily, but the are things inside and out that need to match, not always easy. They do now make custom sizing, so see if they do them in the style you need. Probably pricey, but consider the cost of resizing openings.