I've never bothered to check the epc for radiators but now I did. Only 1 part number for ae85/6 on a MT and one for an AT.
Its the same between all versions around the world... which would indicate that at least for every MT ae85/6 they all came with a single core radiator standard. If its twincore, it will be aftermarket (or maybe an AT radiator, but i've never seen an oem AT radiator so who knows).
I guess that means my twincore that looks oem is prossibly a koyo as told by the previous owner....