I don't know that I've ever seen a "G licence" on any tranny juice I've ever used, it's not on the Amsoil that I've been using. Has anyone seen it on Royal Purple or Mobile 1?
Amsoil is a universal ATF like Mobile 1 & covers GM, Ford, Chrysler & most import applications.
I do know that after using Amsoil for 20k in mine, it was spotless inside when I dropped the pan, with very little metal debris on the magnet.

I'd stay away from blends in favor of pure syn.