RLM 76 Version 2 vs Ulthuan Grey

How close are they?

ΔE 6.0, close: similar, with a visible difference side by side. Ulthuan Grey is a little lighter than RLM 76 Version 2.

Can I use Ulthuan Grey instead of RLM 76 Version 2?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Ulthuan Grey is a little lighter than RLM 76 Version 2.

Can I use RLM 76 Version 2 instead of Ulthuan Grey?

The same difference applies the other way round: RLM 76 Version 2 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.