Light Ghost Gray, FS36375, is good for the gray color, just about any sand will do since the sand color was locally bought in Saudi for them.
Some additional info...
All AH-1Ws were originally painted in the USMC tri-color (black, green, gray) camouflage scheme that first appeared in the mid-1980s. Within a couple of months of arrival in theater, the parent wing directed that the only acceptable colors for helicopters were all sand, sand/brown, or sand/gray. HMLA-369, "Gunfighters", deployed to Desert Storm with 18 AH-1Ws and 6 UH-1Ns. They chose to use the sand/gray paint scheme. The sand was applied over the black and green of the tri-color paint scheme. The original gray of the tri-color camo was used as the gray of the sand/gray scheme; any markings that appeared on the original scheme were still visible. Therefore it was common to see half a stencil visible on the gray while the other half was covered by sand.
EDIT: Sorry, I didn't actually answer his question. Here goes again...
Prior to Desert Storm all HMLA-367 aircraft were repainted sand/brown. The only visible markings were black Bureau (BuNo) numbers (tail) and MODEX numbers (side). HMLA-367's assigned side numbers for their ten Cobras were 120s and 130s. Their 18 UH-1Ns were assigned numbers between 100 and 117 (8s and 9s are not used in side numbers). The best colors to use are: Testors Model Master Sand, FS 33531, and Military Brown, FS 30117.
The decals in the MRC kit are for versions of an HMLA-367 Cobra in Desert Storm sand/brown scheme or an HMT-303 (training squadron) Cobra in tri-color camo. HMT-303 always uses 400 series side numbers. The picture on the side of the MRC box is inaccurate in that it shows the tri-color decals on top off the sand/brown paint scheme. To be nit-picky, if you choose to use the tri-color and depict the model with a full load of ordnance, do not use the HMT-303 tail letters (QT). The training squadron does not use TOW or Hellfire.
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