Removing / replacing end tanks is a complicated not always successful operation that takes special tools. ( The tabs are usually partly cracked during the initial bending and won't survive another open close operation. )

My 97 SL had weeping end tanks and I contacted Behr for service centers. Tools to do the repair are not really out in the wild so I ended up replacing the rad.

Years ago I has a customer with a Renault Fuego that removed the side tanks and epoxied them back on. It seemed to work as long as I saw the car.