Thanks for looking into it, but I had the unit upside down, so it's actually the left hand.
Also when I put the knobs on it, I see the inner and outer rotate, and the outer also clicks in and out.
I haven't had a 66 with an am radio since the 70's, but I don't recall the click function.
Seems a LH am potentiometer won't do?
I also need the case to dash mounting brace with hardware, a power in and speakers out pigtail, and the mounting hardware for behind the knobs.
Next step is to put together a list of radio repair shops to try for parts.