Thanks Darrell, the only reason I asked is because a buddy has several in various colors, a dark tan, medium blue, dark blue and a burgundy. He believes they are from Oldsmobiles or Buicks, but they may even be from non-GM brands (he had a mis-spent youth and owned several blue ovals....). Some have Niagara Plastics on the back, some don't, but I believe Niagara supplied many manufacturers regardless.
So just got me wondering about 67-69 grommets.