Here's the original sale listing on it's own site, heel pic can be magnified more than the above:
https://banjowarehouse.com/product/1964-guild-d-50-acoustic-guitar-brazilian-rosewood/
Probably should have said "Better close-up"; I've got a 21" diagonal display already and still can't get it big AND clear enough to tell.
Problem is from that angle, can't really tell if it's actually displaced wood or a scratch, but it definitely appears like bare wood is visible in that "crack".
The heel cap looks ok and not displaced too, though, which I would expect to see if that was actually some kind of displacement crack, so I don't
really think it is.
It actually looks like a scratch to me, which would be no big deal and even easily fixed with a drop-fill line of NCL, just to seal the wood.
(Same for that ding on the back of the neck if it bothers you, although for that one I'd probably want to get a genuine touchup to included sanding/polishing to get the neck smooth again, I'm just fussy that way.
But without having the guitrar in hand to use a magnifying glass on, I just can't tell.
but more important,
Bonnevilles' pics are textbook examples of what to look for to determine if neck angle is good.
The only additional comment I'd make is where he shows a measurement of string height above the soundboard on the bass E, is better measured at the center of the bridge (at the D string) where bridge (and saddle assuming it's properly profiled) is normally at its tallest.
That's the combined height of the bridge and saddle which
is "ideal" at 1/2" as he shows, generally speaking, of which the saddle height is "ideal" at about 3/16".
That allows for good break angle of strings which in turn allows optimum transfer of string energy through the saddle and bridge/bridgeplate into the top.
And sure those are "targets" subject to the build tolerances in any given instrument, but generally a 32nd to a 16th are the limits of tolerance before a given measurement might be considered "low",
but for saddles take into account an owner's preference when it comes to saddle height, they may have it cut pretty low to get really low action, as he points out.
That's why the bridge alignment test is the test for neck alignment, but knowing a bridge is ideal at aobut 5/16 also helps determine if bridge has been shaved to compensate for bad neck angle.
Sometimes that could be an appropriate "fix" at the expense of some sound output, particularly for low-value guitars, otherwise it's truly just a method to postpone the expense of a fill reset.
And means a new bridge will be needed at re-set time, as well.
Also note the pic showing "nut width" may be a bit deceptive (iI looks like it may actually be measuring the nut and not the fretboard.
The term itself is deceptive because nut width is actually the width of the
fretboard at the front of the nut, which is how the nut width is defined.
BUT if the nut is slight over-or underwide as can happen especially if replaced, it is no longer an accurate measure of the true nut width.
This becomes relevant for example, in trying to determine if the nut shown above is actually an over-sized 1-5/8" (which should be 1.625") or an under-sized 1-11/16 (which should be 1.6825).
And keeping things interesting, because necks were given final shaping by hand,
slight variation from spec on nut widths is a given in vintage Guilds up through close of Westerly, at least (tolerances, again)
There were even occasional 1-3/4 nuts produced, and in fact an early run of D40's and D50's actually got 'em, but by far the vast majority of Guild flattops were spec'd with 1-11/16 nuts.
Knowing how wide the
fretboard actually is lets you know if a new nut with better slot spacing will be viable on a piece you're looking at, if nut width is as critical to you as it is to a lot of folks.
That '64 does look pretty good, if it shows good neck alignment I'd think it was a real peach.