A friend of mine told me recently that he read in a GM parts interchange book that 70 GS frame is listed by itself. That is to say it does not crossreference with other A body frames including skylark. Does anyone know this to be true and if so what is the difference?
Yes, this is true. The GS455 was supposed to be made of a thicker metal. In 71-2, the frames were the same. You can use any 70-2 frame if you need it.