I think there are a fair amount still in exsistance.
At the upcomming Torex auction I believe they have all the 1937 "SPECIMEN" notes graded by PMG (
) but they are all Unc or higher.
Just so you know I am not sure about how many of these are still in exsistance but I did see '37 "SPECIMEN" notes at the CNA and Torex. Just My Opinion!