All the model 1937s shipped to Brazil before WWII had the then current flat top frames with square notch sights. A large portion, maybe a majority, of the model 1937s shipped in 1946 utilized left over WWI round top frames with U notch sights.

Because their’s is lower than the lowest reported in the SCSW or the factory history letter included with 1937s distributed by Navy Arms, many members have asked if their WWI framed 1937 has the lowest serial number. The forum administrator, Handejector, recently posted about one with a five digit s/n, 8xxxx IIRC.

A more interesting tid-bit would be if you could document your 1937 was used by the Brazilian expeditionary force sent to help the allies in WWII.