If you look at the Vintage-trek.com site, the N2F3A12 means 610, 613, or 614, 21" frame, stamped in June 1983. Being a 61x the main tubes are double butted 531 and the seatstays chainstays, and fork blades are either straight 531 or straight CrMo of some other origin. I've had one of these from 1984 since it was new. Sometimes I like and sometimes I don't. I've had mine in many different configurations, it's my mule.

This info is all from the Vintage Trek site. There is also a section on colors and paint combinationsversus year and model. You should go and read that section of the site.as well. It might not all make a consistent story, but these were made nearly 40 years ago. A lot could have happenned to it.