This maple neck came off of a 3-bolt 1975 Fender Stratocaster with the pictured backplate (#569055). It is in overall VG/EX condition, except for finish issues and flaws caused by water damage and attempts to remedy it on the headstock. I will post lots of pictures and information here to hopefully answer everything I know, since I bought it this way (read: the damage did not happen while in my possession).
As for dating the neck-- there is only a hint of a neck butt stamp, although I can see a very faint view of what was likely numbers there. There is a bit of green ink and a hand-ink-written "J". From research, what absolutely assures it is 70's is the "R. Bush" stamp and #11 inspection green stamp. R. Bush worked for Fender during this era and you will see this stamp on other necks from ~1975. The neck came on a 1975 Strat that I still own but wanted a rosewood fingerboard on. Given the features (no serial on headstock, and what it came on, I'm going with 1975).
As for the neck condition and history-- it is really very clean from a play-wear perspective. Sans the water damage, I would actually call it "excellent". The neck is straight, no warps, no cracks, no breaks. The truss rod works fine. In fact, it played fantastic on the black '75 it was on, no issues at all. It has been re-fretted, there is clear evidence of that on the sides and fret edges. The exiting frets are still in great shape and have most of their life left.
The back of the skunk-stripe neck is very clean, really not much wear. The "F" tuners and ferrules look original and are like new. The nut looks original. The 2 string trees look original. I inspected the neck with a black light and could see no issues. Fender used polyurethane finishes on these, and that does not glow green, so it is impossible to know if finish is original. But it is poly. There are no extra holes (i.e., for a 4-hole application).
Now for the headstock "mystery"... There is some natural finish checking on front of headstock (not uncommon mojo here). There is what appears to be water damage, finish checking and dark finish "stain", probably from an attempt to repair where finish did not take because wood was damaged from water. (This is what my luthier guessed happened). Truth is, if it bothers you, look on. But it is not too bad from the front of guitar.
In any event-- this is a genuine Fender 70's neck that is in good shape with nice frets that happens to have a finish anomaly. I am pricing it accordingly and will entertain offers. If you price similar-era necks, it is not uncommon for them to go for $1500 in nice condition. Maple necks do not age well and many of those offered are in poor or fair shape at best. This one is actually way cleaner but has the issue. The tuners alone are worth $200 and the neck has vintage mojo and functions perfectly. In theory, you could have someone blend-refinish the back of and top-front of headstock, but I feel it is better left alone. I'd rather sell it "as is".
Listed on Reverb for higher price if you want to check me out there.