Dark Mud vs Golfag Brown

How close are they?

ΔE 8.3, close: similar, with a visible difference side by side. Golfag Brown is a little lighter, warmer than Dark Mud.

Can I use Golfag Brown instead of Dark Mud?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Golfag Brown is a little lighter, warmer than Dark Mud.

Can I use Dark Mud instead of Golfag Brown?

The same difference applies the other way round: Dark Mud is a little darker, cooler.

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.