Changing Coolant

[shamandog]

I recently aquired a 1988 560sl in beautiful condition.

I want to change the coolant. I know where the drain plugs are, but how do you refill it?

This may be a dumb question, but I can't figure out how to replace the drained coolant. There is no cap on the radiator like the old style cars. And the reserve tank for the coolant only has the narrow tube leading from near the top to the radiator.

I hope I am not missing something very simple???

Thanks for you help.

Richard