It came from the factory without a hose on the expansion tank there, but some owners like to add one. If you want it to look original, don't add a hose.
And let me add that is one gorgeous SL. Congratulations, Ed.
(One more thing -- since you've gone berserk on the engine bay, you should get the right hoseclamps. Either Norma or, better yet, Gemi.)
Douglas Kim
New York, NY
280 SL #016220