I looked through my head rebuild pictures, but couldn't find a pic of it. It should be a relatively large O-ring. Somebody correct me if I am wrong. I can't remember.

At the end in the rivet?

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k