factory style gas cap, '78 stepside

[urbex]

Have a '78 step side C10, and someone lost one of the original gas caps to the truck, have yet to be able to locate one. The original ones had that handle/ridge molded into the cap, and all the replacements are a smooth style, which my GF has a hard time unscrewing from the truck (in her defense, the thing does fit awfully snug on the truck, even I've had difficulties getting a good grip on it at times).

I've been looking online, and haven't yet found an original style replacement as a new reproduction or NOS part. Does anyone make them, or is the only option to find one used and recondition it?