There was an old ac unit built into the wall when I moved into the house. It was nasty. I can't seem to find a unit that fits. The dimensions are 18 wide by 14 high. All in the wall units I see everything are bigger. The width of the wall is about 6 1/2. What are my options here? I don't want to have to expand the opening past the studs or framing someone built. It is a load bearing wall with shingles on the outside. Thanks. The wife is not happy I didn't take care of this in the spring.