I've got a 67 SJ FB from Dec 66. The cover goes all the way to the box like your older model. This particular design is a single long shaft that is actually part of the steering gear assembly. The tube is installed over the shaft. There is no rag joint in this design.
I think that all 64-66 are this way. I thought that 67 was also, with the exception of the tilt wheel option.
With the tilt wheel, the design was modified to have a steering box with a short shaft, and the steering column had a separate shaft. A rag joint joined the two.
It looks like yours is another variation, a non tilt separated shaft model with rag joint. I have not seen one in a non tilt car in 67.
Since the ragjoint could provide a decrease in vibration, perhaps there was a change over to that design as the standard. Not sure why yours got that when built 3 months before mine. Stranger things have happened.
Perhaps yours originally had a tilt, and a previous owner removed it and installed a different unit. Perhaps from a 68? Do you have a Marti?
In later years they went to the collapsable column design and moved the key from the dash to the column, all safety features. All of those have a short shaft steering box.
John