ΔE 11.8, fair: the same colour family, but not a straight swap. German Gray is a little lighter than Thunderhawk Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). German Gray is a little lighter than Thunderhawk Blue.
The same difference applies the other way round: Thunderhawk Blue is a little darker.
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 Thunderhawk Blue on the colour wheel See German Gray on the colour wheel
All matches: Thunderhawk Blue equivalents · German Gray equivalents