I finally got around to getting some info on the Vintage Trek website. Although, as several folks have noted, the Mylanta-Green paint scheme was for the '84 model year, the serial #108105 of the frame puts the date of manufacture as 1983! Whew, just under the wire, too.
Now I can bring it to the Vintage Ride without shame.
Bill Silverman
Pasadena, CA, USA