[njk53]

You have to get the lock cylinder out of the ignition before the retaining ring can be unscrewed. Take a paper clip and put it in the small hole in the face of the ignition and turn the key. Once the cylinder is out the ring will come off. I have a 66 also and learned the hard way screwing up the retaining ring. If the key is not the right one buy a lock pick set from an online supplier.