Original oil coolers are called Drawn Cup. The prototype of them were fabricated Bar and Plate coolers as found on the 911R's. The bar and plate coolers have cores, headers and tanks with fittings installed in the top tanks. The drawn cup coolers have staggered cores with no tanks. They are pressed together and oven welded. They were fragile coolers. The tooling was very expensive for this kind of cooler but with large production made it feasible. If your coolers are bar and plate cores, how are you going to have headers and tanks? Gled