Date-coded serial numbers are typically found stamped on the back or top of the headstock, and "Made in USA" is stamped next to the number starting in June 1967. The next digit = last digit of the year (1966 to 1972: 6,7,8,9,0,1,2).
The remaining digits = number of individual instrument, probably.
You spot a '79 in a local shop, or online, but how can you be certain it is a '79?
The Gretsch-GEAR database exists to get it right: to document the actual serial numbers, to determine once and for all what was built and when, and to harness the collective knowledge of thousands of Gretsch fans to put the pieces together.
and both were being made at the same time from 1994 till 1997.
This means that the the serial numbers starting in 1994 ran consecutively on both the MIJ and the CIJ models while the MIJ logo was being phased out.
They were designed to help identify the approximate manufacturing date of the guitar.
For example: a guitar whose serial number begins with the letter and number "E8", would have "theoretically" been manufactured in 1988 (E = in the Eighties, 8 = the 8th year...