Identify Original 2 & 3 Core Radiator by Dimensions?

[Ironhorse]

Recently was at an auction with a LOT of older car and truck parts. Acquired a radiator which is marked Harrison with no tag or numbers stamped on the tanks. Looks to be good shape altho used. VERY similar to what I recall I replaced in my truck which was the original 2 & 3 core, rotted and was able to replace with a 4 core setup. Any identifying marks I can use to be able to tell it is GM original to that era truck? Dimensions between tanks, height, etc , the necks seem to be in correct position altho lower neck is straight and not curved upward. Seems to be in good condition altho shows has been used with some scale inside. Any tips to positively identify original application. Box it was in was marked "4 pickup" LOL