Sako: There is no 2g prefix listed in the Standard Catalogue of S&W. Is the stamping the same as the rest of the serial number? If the serial number is 739xx then it is a .38 special model of 1905 4th change, probably manufactured between 1940 & 1942.The 4th change was produced from 1917 to 1942. To help refine it down, S&W made the British service revolver concurrently in the same serial number range of 700000 to 1000000 during this period.
I assume the .38 S&W has a five shot cylinder on a smaller frame than the .38 special, if so then it is either a prewar .38 Regulation Police. These were made between 1917 & 1940, in a serial number range 1 - 54474. The round butt .38/22 Terrier variant was introduced in 1936 at serial number 38976, so your gun should date from 1936-1940.