Hi Lycia,
Is there a round head badge on it? Are there 4 digits stamped into it? The last two are the year of manufacture. Also, the G number could indicate a 1985 Giant (Taiwan) built frame. That number is usually on the right rear dropout though. Pictures would be nice.
http://www.trfindley.com/flschwinn_1...90/index4.html
Welcome to the forums.
Jerry