If by Gulf War you are referring to Operation Desert Shield/Storm in '90-'91, there was no FS color. Most vehicles were quickly repainted as they arrived in Saudi Arabia with locally procured sand colored paints. Many of them were cheap, latex house paint and didn't last long. It chipped and peeled a lot. So you can basically use any sand/tan color.
Currently, the official color is CARC Tan 686A FS33446. There is no model color that matches this exactly. Additionally, the color fades quickly and doesn't look like FS color for very long. The best model paint color is FS 33531 Sand.
Gino P. Quintiliani - Field Artillery - The KING of BATTLE!!!
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"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." -- George Orwell