as far as I know the filler neck is the same as the gas trucks, just with the guts removed. I know the filler cap is identical. The Diesels are not easy to find here either!

The Hyundai Galloper was a Pajero knockoff with mismatched parts and pieces from GEN I's and GEN II's all bolted together. The fact you have a KIA version of the engine is new to me, not sure what KIA built overseas.