ebay seller searayman13 / explorersport13 (same seller)
https://www.ebay.com/itm/VENT-LOUVER...item1caafc7fed
He's got bright white, white, grey, and black.
They are identical to the originals on my 77 seafari; they are new old stock; I spoke with the seller, who happens to be in my neck of the woods, and will buy more in the even I crack one. Highly recommended.