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It looks like your tank is a little low if it's a pressurized tank. And a pressurized tank is supposed to used to fill the radiator because it usually mounted higher than the top of the radiator. And it usually has a larger hose that comes of it to fill the radiator. (I'd tee off a heater hose possibly if I were to install a pressurized over flow tank in our old cars). Good luck with yours. Does it have a hose inside that goes to the bottom is it's not pressurized and vented?