Well, maybe not so fast...
The D17 fretboard width at the nut is 1.662" / 42.20 mm...
the D30 fretboard width at the nut is 1.718" / 43.63 mm.
Fwiw, serial# on the D17 is AL100495, bevel stamp MAR 8 1985
In case it was never known by the previous posters, or simply forgotten, the source of all this variation is that
every single neck in Westerly was
hand-finished on a belt and/or cone sander.
Sure they had profile templates, but no 2 Westerly necks are going to be identical except by extremely low odds of coincidence.
For dreadnoughts the overwhelming majority of 'em were spec'd for 1-11/16" with some known 1-3/4" specs, like a batch of '64 D40's; and some early '90's DV models ('93-'94 IIRC) that are definitely 1-3/4 even though it was never a catalog spec for those.
The 1-5/8 was found primarily on very early (late '50's) M/F-20's (IIRC) and later acoustic-electrics from the late '80's through '01, like F4ce and F65ce.
It was also common on electrics.
So on any given day it's possible a guy was given different batches of necks varying in both scale and nut width and maybe just needed to "get warmed up" after a change, as well as there being different guys finishing necks at different times.
I do have a vague memory that there weren't actually that many guys who did neck finishing, though.
Like maybe 3 or 4 over the history of Westerly?
Point being it's not like there was constant change of personnel at the belt sander.