Used 'CORE" grade radiator, marked C9ZE-D or D1, .. etc. 20 inch used radiator from 1969 Mercury Cougar with Boss 302 or 351W or 1969 Ford Mustang with 302 or 351W or engines. This radiator will have the lower tank for transmission lines. Core grade, likely it has been recored at some point in the last 45 plus years. Limited to stock on hand.
Restoring or re-coring OEM radiators is expensive and more for the concours crowd. New or reproduction radiators makes much more economical sense.
Ford marked C9ZE-D or variants on the side strap. Picture shows C9ZE-D1 which has been sold.