The seller had left on holiday when I posted this. He and I have been internet friends for several years. He's played with McCartney, Dire Straits, The Water Boys, Julian Cope, and many others. I can see no reason that he would deceive me. He was quite clear; this is a 5.5 bronze Supra from the '60s. I had never heard of one either, which is why I posted here. He is a major collector, and has many prototypes; maybe this is one. As I said, he is hesitant to sell, so if it were a newer, more common model, that wouldn't make any sense. I will post pics as soon as he gets back.
Thanks for the input.