It is a contracted Schwinn from the 1980's, made by Giant. The serial system on the dropout is from Giant, the subcontractor who built that frame; hence the confusion. I'm not that well up on decoding those - give me a minute to find the charts.

EDIT: Here's the serial chart you want: http://www.trfindley.com/Pg_Later_Sc...%20numbers.htm

G0785 = Giant, July 1985.

You should have no problem finding this frame in the 1985 catalog.

-Kurt