I'm thinking the vehicle you see is the end result of Tremulis working with Peter Bryant and others on the design. The prototype Tremulis refers to, I think, is the 3/8th scale model. But, now that I know who to look for, I know there are other letters and correspondence describing this project. I'll post as I find them.
I've seen these names on other letters (original documents obtained from the author, many, many years ago), but attributed them to the Travoy that Tremulis drove to the land speed record in 1970 (same players, minus Bryant):
It's a small world: In 1973, Tremulis and Bryant both displayed their cars side-by-side at the LA Auto Show. Tremulis with Bill Hamlin's Tucker #1002 and Bryant with his Shadow. Tremulis wrote an entertaining story to go along with that encounter, posted on the Tucker Club's website...