Kurt,
I snapped a couple of photos of the one on my '69. The index groove on the input shaft of the steering box is very light and hard to see. Mine is filled with light rust, but became visible after a light abrasive cleaning.
I had the exact same problem you are having and it was a matter of finding this index mark on the steering box input shaft. On the 69 steering box, the rag joint can slide in anywhere it contacts the splines on the input shaft. I noticed on your second picture that I can see an index mark on the shaft(under the paint), just after the splines -- moving toward the box itself. Here are a couple of photos of the one on my car. Hope this helps.
Phil Woj.
