It was prior to 1958, ala the lack of zip code. Also, I have inspected many of these and they were about 33 1/3% efficient and lasted forever. Made in Holland Michigan down by the lake and Howard Miller clock company. Chad is correct about the use of chrome. The company got started as a furnace manufacturer and morphed into a furnace cleaning company using giant vacuum trucks.
http://www.hollandprofessionalclub.org/wp-content/uploads/2015/10/2017-March-Rob-Sligh-The-Rise-and-Fall-of-Holland-Furnace-Company.pdf
there are dozens of stories about the company and most are about how the company influenced commerce and fraudulent business stuff.