I'm like that too. A really cool '93 archback, standard scale, 1 11/16" nut "prototype" F20 that was a closet queen. It's living with a fellow LTGer SouthernGuild in Oz. I'd love to have another just like it, but will never find one in this condition again.
"FF" serial numbers were only used on prototypes, in this case for the reintroduction of the F20 to the product line.
It had a really unique punchy sound, but at the time I thought that bigger was better (and still do mostly). I've had saved searches on eBay that have turned up nothing for years. I guess they didn't make many like this!
I think I bought it about 1967-8 - I was third owner - the guitar had reputation of bad neck so I got it cheap - that was first time ever I've seen a guitar with adjustable truss rod - so naturally I attacked it - Voila' - nice playing straight neck.
I sold it about 1988 - interest rates were skyrocketing and we had to take care of mortgage . . .
My theory is that the guitar makes sound waves that travel many miles causing people in the region to say to their friends as they take walks, "did you hear that?" "Hear what," the friend replies. "I guess it was nothing, it just sounded like some kind of music." "To me, it was, The Sound Of Silence."
A chuckle and they keep walking.