To determine the date of manufacture of a 70's-80's GE product, look for the Date Code sticker in the battery compartment. It will have a 4-digit code; the second digit is the last digit of the year. You know it's made in the 80's so if the second digit is 3 (for example) the year would be 1983.
Source:
http://www.antiqueradios.com/forums/...p?f=4&t=179177