Some random thoughts on Dove and Navy.
The Vac era pencils are celluloid and prone to discoloring.
The VAC filled Grey pens are prone to all sorts of discoloration. Often being confused with Nassau.
It is known (among long time collectors) that a number of grey pens were dyed other colors.
David Nishimura turned up a group of barrels in the wrong color of grey. I'll let him chime in if he so chooses.
If unusual combinations exist like a Nassau Aero 51, one has not been found to the best of my limited knowledge.
True 1940 or very early 1941 production pens are often in colors that are off the norm.
San Francisco International Pen Show - They have dates! August 23-24-25, 2019 AND August 28-29-30, 2020. Book your travel and tables now! My PM box is usually full. Just email me: my last name at the google mail address.