Color varies depending on era (Desert Shield/Storm vs. post ODS). Some of the shades used during Desert Shield varied as they were procured locally stateside or once in theater. Color was standardized at the end of the war and as tanks and vehicles became manufactured in the color. The color sand seemed different when factory applied as opposed to a 3 color NATO tank being painted by the various installation maintenance facilities.
The tank weathers in the sun with the upper surfaces fading to a lighter shade and the sides stayng much yellower.