The only known exception is that the numbers are sometimes found stamped in black ink (ie NOT impressed into the wood).These inked numbers have been the subject of ongoing debate, however, it now appears they are mainly from 1980 & 1981.Dates and source codes to help aid and determine the age or year of production of your vintage guitar,amp or other electronic instrument. Source-Date Codes On American made vintage guitars and gear, the pots and speakers provide an excellent opportunity to date a piece of equipment by referencing their "source-date code".
Some other Greco Gibson-like models from the 1970s had a different headstock design, more like a Guild headstock design, that had a Greco logo with equally sized letters.
Starting in 1979, the Greco "Super Real Series" was introduced which made available high standard replicas of Gibson and Fender models.
In 1982 the Greco "Mint Collection" was introduced, which continued the high standard of the "Super Real Series".
I you look closely at this list you will see that Tokais numbering system raises potential problems each time there's a change of decade.
In particular, SN=00xxxxx (ie beginning with two zeros) may indicate either 1980 or 2000.