Here are three pictures of a Sept 11, 64 San Jose build Fastback trunk torsion rod. To install, the rod was "hooked" into the RH trunk hinge and slid into the slot in the LH trunk hinge up to the bracket. Note the clip. It looks like the clip used to hold the AT cooling lines together. At the same time as the rod is slid into the LH slot, the RH end is slid into the swinging arm. It is held in place by a 1/4 inch id washer and a cotter pin.
Jim