Not mine https://www.ebay.com/itm/126358298976 I was trying to understand what the “thumb groove” was. Is it the indentation on the front side rather than the ribs in the back?
I guess your right, because my "Cushion grip' definitely does not have that groove on the face of it...
May could have been in a Corvette originally or possibly a big body Buick that had gray int. definitely a rare color
In 1963 and 1964 Corvettes used a 16" three spoke steering wheel with a hard plastic rim, but the soft rubber Corvette steering wheels were all 15".
Here is a report I found on the sport steering wheels. It’s focused on Camaros but mentions Buicks and the thumb groove. http://www.camaros.org/swheel.shtml