Thanks! I missed that line in the Standards. And I have now found where Brattons's advertises a Brass Works brand with that hood rest.Original on 1928-1929 radiators. See the "Restoration Guidelines & Judging Standards", page 3-1, first paragraph.
Don is correct, it is not a bolt on, but I am surprised that some of the catalogs do not add it as a piece that you could buy and have it added to an existing radiator. Just a thought.It is a part of the radiator, not a "bolt on".