A Harmony Model number is generally stamped as XXXHXX. There has also been a conventional wisdom that Harmony did not put serial numbers on their mandolins. I see that is the most likely explanation for the date code. Those instruments built after the shutdown were marked S-YEAR (First Half, Second Half). Those pre shutdown instruments were marked F-YEAR. Harmony apparently shut down for two weeks every July and there would be a rush to complete instruments by the end of June. Everything I've owned (a few dozen) was marked S or F. I went back through my records of instruments that passed through my hands certain I'd had a W in the past. From some recent information that was gleaned from a former Harmony employee that has changed somewhat. The general thought (that I have posted here in the past) is that they were stamped with a letter that stood for the season the instrument was built (Summer, Winter, Fall) followed by the two digit year. There has been a conventional wisdom for the last several years as to how Harmony Date Coded their instruments and how they were read.
