I know you are being tongue in cheek Tim.
I will answer your question for Deve.
Although a lot of rebuilt distributors come with an O-ring in the top groove there is not suppose to be anything. That Groove is an air gap to prevent oil from wicking up between the dist housing and the block.
With an O-ring in that groove the distributor will have a hard time rotating with the vacuum advance, IE: not at all.
