But with that said, I believe non-US versions of the HMMWV may have different engines, transmissions and transfer cases sourced from their respective countries.
I don´t think so; overhere in Europe, the Humvee dealers source vehicles from all over the world, and every non-US Humvee I´ve stumbled upon so far (Denmark, Poland, Luxemburg, Spain, even Africa) had the same good old 8-cylinder GM/GEP diesel, either 6.2, 6.5, NA or turbo, the 3L80 or 4L80 transmission, and either the NP218 or NP242 transfer.
Now there are a few "Humvee lookalikes" around the world, that at first glance seem close to a Humvee. Spain comes to mind with their URO Vamtac, but that one has a totally different construction, and a 6-cylinder engine.