This is what it says in the review from the sight that Steve got the picture of the decal from:
The first letter looks like an "I" but I guess it's supposed to be a "1".
"Finishing options are provided for two "generic" US Army vehicles in Iraq, 2003: however, both have bumper codes and therefore can be identified. One is an artillery survey team track, HQ-35, from 2-3 Artillery Battalion, 1st Infantry Division; the other is an armored ambulance from HQS Company, 2-7 Infantry Battalion, 3rd Infantry Division. Both are finished overall in Iraq sand."