Yup, Ma Mopar was all over the map on this. But here’s the deal. There’s no benefit to the steering shaft being able to do anything other than spin. So putting a bearing at the bottom will hurt absolutely nothing. The set screws won’t change the ability of the steering shaft to collapse in a crash. The upper bearing that goes between the shaft and housing is very thin, so, it will not prevent the bottom of the steering shaft from moving around. And that can cause wear up top. The steering coupler is designed to allow movement, so, that’s not gonna do it either. Putting a bearing at the bottom of the column jacket will keep the steering shaft from moving around, which will make your steering smoother and more accurate. It doesn’t constrain anything that needs to move either.
Can you live without one? Sure, clearly a lot of cars left the factory without a bearing there. But some cars, most of them heavier duty applications, got them. So adding one doesn’t hurt anything either, and it will probably give you a smoother feeling action on your steering wheel. And possibly keep you from working that upper bearing loose in the housing, or peeling that little upper bearing apart. And yes, I have seen the upper bearings worn out and falling apart.
So you can do whatever you like, I wrote this up so people could see a cheaper option than the factory replacement bearing and an upgrade for the cars that didn’t come with them. The ER16 bearings are cheap, you can slide them up into the jacket so they’re not visible, so the only externally visible change is the set screw so it’s a pretty small change if you’re worried about originality.