Branda had these one day and the next day I got a call saying they had none. There are some on EBay at 3/8" and 9" long, but the hook part doesn't look quite right. They are not reproductions though. https://www.ebay.com/itm/264030627300
These Ebay examples look just like my early-November San Jose J-bolt. Mine is a Mustang (not Shelby) but my hook looks just like this one and my J-bolt is 3/8" diameter, 9-inches long.
(Note: the picture of my bolt was taken at an angle that distorts the hook, making it look like a sharper angle but is actually closer to a 90-degree hook angle).