Yes, there are bits of information scattered here and there.Certainly, the movement dating chart developed by Gruen collector Charlie Cleves, of Bellevue, Ky., almost 30 years ago was a good start, and pointed many collectors in the general vicinity as far as dating a given specimen.The Style Number Dating Table has been extended back as far as it will go, which seems to be 1925.Last year this table was incorporated into the Online Style Number Tool and the Windows software version 4.0, but the table itself wasn't published.Should be no surprise that the graph shows the first Caliber 311 Style Numbers started in 1935 and they ended in 1937.
Download Ver 4.0 of the free Windows program that provides date and other information given a Style Number.
These and other brands have volumes of material and definitive movement serial number listings that allow for precise dating down to the year, and in some instances even the MONTH, in which a given specimen was manufactured.
Not so for Gruen, being the "orphan child" without a birth certificate because of a rather complicated method of serializing their movements, the records for which have been long lost, and most likely destroyed.
You want to match the date with the correct use of that date.
Here are the 3 different dates that can be found on a Gruen watch.2.