its a 1990 5.0. I recently had a new radiator installed and he told me that I am missing a rubber piece that goes underneath the radiator and without this it will leak. And it has. Any ideas on what this piece is called?

 

the only rubber things i can think of is the rubber pading in the radiator suport, with out that it could vibrate and couse a leak do to metal on metal. is it leaking from the lower part of the radiator?