Not a Huebler
With all respect to your partner, the joint looks nothing like Hueblers. It is brass, and the right thread, but its piloted, has the wrong bumber, and also looks tapped. I have several and its unlike any of his joints that I have ever seen. As far as I know Hueblers have always had 5/16 x 18 non piloted joints.
Good luck in your identification, as I have no idea who would have made that. The only assistance that I can add is that I do not think its a Huebler.
JM