I'm happy to have found this thread as it has cleared up a great amount of confusion and wonder. I picked up what I think to be a FT570SB from a friend, who found it in a basement, sitting against the wall at a very severe angle, and time ( as well as kids continuing to tighten and retighten the strings) had caused the neck to separate from the body; a problem, I have since learned, that has plagued many a FT570 without the root causes I have just stated. The label inside the body, once blue, had either been torn off or simply fell off with age.
At any rate, I got the neck repaired, both reset, glued, and then bolted on. I say "bolted on" because the neck was definitely a dove tail neck, unlike the one displayed in the pictures in another posting, and the bolt installed by the luthier who repaired the guitar was definitely an addition, not a replacement.
Was the FT570 ever produced with a regular dovetail, glued on neck, or am I now only 75% sure of exactly which guitar I own?
As you can see by the pictures, it looks like a FT570SB, with the exception of the neck heel.
Any information would be greatly appreciated. This guitar, regardless of where/when it was made and what it may be selling for in the "real world," outplays and sounds better than any guitar I have ever owned.