I always list this puppy on new boards, & so far nobody has any ideas. So here it is again (regret i can't post pics, but i don't think they would add much in this case.) It was battlefield dug in Poland. It's a standard German-style 45mm "blanko" (made without an inset) box buckle, all in brass, brazed post/prong assembly, hook-type catch, unmarked.
My guess is it could be some type of East Euro Gendarmerie buckle.
My guess is it could be some type of East Euro Gendarmerie buckle.