Cleaned-up OLD rag joint coupler connection to power steering assisted gear box (with cylinder like Vette,) and used a steering coupler rag joint rebuild kit to make it work. Should work. I used red Locktite to make sure it would not come apart.
I figured-out this intermediate shaft kit was made to fit a STANDARD POWER STEERING GEAR BOX. Attached a picture of complete intermediate steering column assembly sold for attaching new tilt steering column in a '67-68 Chevy truck.
(The rubber caps were just to keep the intermediate shaft in place as I work installing the rest of the column to includes a D shaft to splined U-joint coupler.)