Sealer Under Rivets?
I have to replace some of the reinforcements on the underside of the body (seat frame and seat belt anchors) of my '67 A.O. Smith coupe. In cutting off the old rivets it looks like wafer discs of a sealing compound were put under the rivet heads. I assume this was for noise and moisture sealing. Two questions- I don't remember noticing this on a 63 SWC I restored (many years ago). Does anyone know with what model year this started? Secondly, has anyone tried to duplicate this when reriveting the reinforcements and if so is there somewhere you can buy the precut wafers?