Apparently serial numbers for Fender acoustics were never archived and serve no purpose in dating a Fender acoustic, at least that's according to the Fender website. This is where pictures and more information would come in handy.
The Fender F115 was made from 1977 to 1987. The Fender F15 was a concert-sized acoustic guitar and was made from 1973 to 1981. So, if the label says "115" and it's a Dreadnought-sized acoustic, I would guess that your acoustic is a Fender F115. A quick google search shows the F115 looking like
this while the F15 looked like
this.