The Kay-built 604 came along... well, I don't really
know why. We can speculate that Sears was selling so many guitars that Harmony
couldn't keep up with the demand, and they called on Kay to fill the gap. Maybe
it was just occasional 'spot' shortages, and the Kay-built 604 took up the
slack. Whatever the reason, the guitar that resulted was close enough to what
was depicted in the catalog that there apparently weren't many arguments, and
collectors get something unusual to keep an eye out for.