[Roadsters] Upper ball joint question

[M M]

Hi All,
I'm in the process of rebuilding my front suspension and noticed what appears
to be a seal of some sort on the top of the ball joint.  Specifically, a thin
piece of rubber was sticking out of the thread where the center section screws
into the body of the ball joint.  These are ball joints I bought from a vendor
about 20 yrs ago that otherwise are perfectly good.  Is anyone familiar with
this?  Are they there to prevent grease from escaping?  If so, can I use RTV
gasket maker or do I need to buy new ball joints?
 
Thanks.
 
Mike Gleeson
68 2L