My in-laws own a really nice lake cabin that dates from the mid-30s; the shower head recently fell apart. I now find that the shower arm ends in a
5/8'' male fine thread, while all available shower heads are 1/2" coarse. I badly need an adapter to make that connection (5/8" fine female to 1/2" coarse male) but have been unable to find one. Any idea where to find one, or failing that, a 5/8" fine shower head?