Yeah, your guitar is a bit of an oddball... mainly due to the headstock logo IMO.
The '66 pot dates can be explained fairly easily, since as has already been mentioned, there are a lot of examples of fully original Fenders from later years that have pots with '66 dates on them.
Another thing I find somewhat odd is the second string tree. Most Fenders only had one prior to the early 1970's, although adding a second one is not an unheard of user modification.
According to this site:
http://www.guitardaterproject.org/fender.aspx
your neck plate serial number dates from 1968.
According to this site:
http://home.provide.net/~cfh/fender.html#serial
It's a '69.
According to Fender's website (
http://www.fender.com/support/usa_instruments.php ), it's a '68-'70.
I have never seen a Bronco with a pre-CBS spaghetti logo on it. I'm not saying it couldn't be factory stock, but it's enough of an oddball that I'm suspicious that it might be an old refinish on the neck and a replacement NOS or reproduction decal. The logo itself looks HUGE to me - much larger than the spaghetti logo on my reissue and vintage Strats. I doubt the neck or guitar is a forgery - no one is going to try to fake a Bronco neck; or at least no one would have done so ten or twenty years ago.
I'd recommend two things for starters. Unbolt the neck and see if there is anything stamped on the neck heel in terms of a date. Fender used rubber stamps to date their neck heels in the mid / late 1960's, and it should have something that indicates the model and date. If there is anything either written or stamped on the neck heel, please post it here and I'll decode it for you.
While you have the neck off, you can use a SMALL amount of lacquer thinner on the end of a cotton swab / Q-Tip to see if you can "melt" the finish on the back of the neck heel (in a spot that will be invisible when the neck is reattached; such as near one of the four bolt holes). If the finish melts from the lacquer thinner / naphtha, it's lacquer - if it doesn't, it's poly. Fender stopped using nitrocellulose lacquer around 1968... of course, that doesn't tell us for certain if it's been refinished by someone with lacquer or not... but it will let you know if it's finished in lacquer or poly, and that's yet another fact that can be useful in helping to accurately "date" the guitar.
Finally, if you can take some close up pictures of the electronics (especially the pots and output jack), I can probably let you know if they are all original or not in terms of the wiring and solder joints - which again, is further evidence of originality / date vs modifications / tampering.
My best guess based on the pictures is that it's a lacquer neck refinish with a replacement logo, or a factory finished neck with a leftover spaghetti logo (much less likely but not impossible) and the guitar dates from circa 1968.