New to Classic Cars / 74 Duster Restoration

The ???? part is the Steering Coupler and what you do with those is replace the "shoes" inside, pack it with grease, install new pin, and a new seal and reassemble. You can get steering coupler rebuild kit with all the needed parts:

http://www.moparsupercenter.com/mopar-steering-coupling-rebuild-kit-4443436ac4443436ac.html

Try searching this forum and you will likely find a thread with more info on the coupler rebuild. As for the shaft pull the column and sand that shaft down, paint it, and put it back in. I had to squirt WD-40 followed up by oil into the lower area with the column sitting straight up on the steering wheel to free that lower bearing up on mine. Then I just put it back on the car works great.

You can also replace the foam seal on the firewall for the steering column if you decide to pull it out. They are readily available reproduced.

A lot of knowledge here on this site so keep asking questions and learn to use the search feature on the forum you can find almost any info you need using that tool it is very powerful.