I had the Revell 1/48 CH-53 kit when I was a kid, the packaging said it was a G variant, it came with US Marine and German army decal options. That was in the mid 1980's.
In the mid 1990's I saw a 1/48 CH-53 in Revell Germany packaging on a store shelf, the box art depicted a German army variant in overall white with UN markings on it. I suspect it was a reissue of the same kit.
If you find the old Revell release of it just be aware that the fit could be better and the rotor hub area is substantially simplified in detail. You'll have your work cut out for you.