Not rare "in the day" , could be now since so many were recycled. Ansen Engineering was the first to offer this altered copy of a Halibrand mag wheel. Others like US, ET , Shelby , Rocket , Apilance , Western and others made them by the millions. You could buy them for as little as 29.95 at one local speed shop chain. Some have a logo or name on the back side of the wheel , some don't and some were made in Japan.
I may not be a GT350 Member but I am a GT 350 owner , stay thirsty my friends