If a mudelf made the title "how to date a Fender F 55-12 acoustic 12-string" it might get more hits. I imagine people think from the titme that it's just another "I've got a great guitar" thread.

You are right that the Fender website is crap - saying only : =

F55-12
1972-1980
$270
Spruce top, bubinga back and sides


And asserting that they have no number records. Unbelievable!

I know that there are sites out there with much more information about the Fender amps than Fender themselves have so it may be worth a thorough trawl of the internet and if you do find a site with info about Fender acoustics (I have seen many crap and one or two good, one spectacularly good) pm them or try their forum if they have one.