ΔE 10.4, fair: the same colour family, but not a straight swap. Slaanesh Grey is more saturated than Grauviolett RLM 75.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Slaanesh Grey is more saturated than Grauviolett RLM 75.
The same difference applies the other way round: Grauviolett RLM 75 is more muted.
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 Grauviolett RLM 75 on the colour wheel See Slaanesh Grey on the colour wheel
All matches: Grauviolett RLM 75 equivalents · Slaanesh Grey equivalents