Two Bobs Aviation Graphics may have some. http://www.twobobs.net/
Another option would be to contact Revell/Monogram and see if they have a set for the USMC or USAF version. It has been issued over the years as both types.
He could also get any generic USAF or USMC decals and piece them together. Two Bobs could probably help again.
Simple black stencil decals can be easily made on a home computer using the Testors Decal Kit as well.
Good luck.
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