Pharold,
I can't help you with a lot of technical stats & accurate dates but I can tell you the GF 60 is smaller, maybe 85% the size of the F 50.
Size difference is noticeable, GF 60 has a more comfortable, small body feel. Nice guitar, sweet voice, mine can take some pretty aggressive licks & play clean, pretty loud if you get after it. Easily the classiest sound of the acoustics I have. I paid way too much.
It needed some work, had to have the bridge shaved to get it to play nice. Originally the bridge was uncommonly thick, looking at it you'd never know it's been altered.
Here's a picture of my GF 60 next to a G 37. G 37 is a pretty standard Dreadnaught size