2 style radiator caps- where to buy what I need

My 65 had the same rubber overflow line (smaller gauge) clipped to the side of the rad. I thought for sure there was something on the end but nope, a dribbler. It should not even dribble under normal working conditions. Even when the motor gets heat soak, the pressure rating should not exceed the cap or you would be topping the rad off every 3 months. Most AL aftermarket rads dont use a Mopar cap. That $25 cap looks right.