I dont specifcally remember the #5 rib location deal but remember there are sometimes multiples of a rib number, this is usually the shape and not the location. There could be several # 3 ribs or whatever. On a Goldberg Cub there are instructions for a clipped wing version or the standard wing. Read through the instructions very closely while looking at the blueprint, it will usually be easy to figure out. The biggest problem people have with Goldberg Cubs is accidently building 2 right fuselage sides or 2 right wings. Pay close attention to the center section as that is where it gets a little busy. I have built 2 Goldberg Cubs and they are a great first build. Some of the Lazer cut parts dont fit perfectly but a little sanding to square up the parts will make them fit good. Hopefully someone else who is currently building a Cub can help out too.