ΔE 14.2, fair: the same colour family, but not a straight swap. Gray FS26440 is a little darker, cooler than Wraithbone.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Gray FS26440 is a little darker, cooler than Wraithbone.
The same difference applies the other way round: Wraithbone is a little lighter, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Wraithbone on the colour wheel See Gray FS26440 on the colour wheel
All matches: Wraithbone equivalents · Gray FS26440 equivalents