Couldn't find the thread in which recently I read about the grommets for the third brake light. Someone mentioned ACE Hardware. My light had been flopping around for a while so Thursday from eBay I purchased 8 of them. Came with an allen wrench.
Installed them this morning. Nice and snug. Rubber grommet slipped right into the hole... light... top black piece... couple of plastic washers and the screw. 5 minutes.
I've 3 pair left. They'll wind up in the drawer with all the stuff "I'll use later", or to the first 3 forum members PMing me with a name and address I'll get a pair into the mail to you. Gratis. Postage included. Allen wrench not.