Help with loose steering/steering shaft bearing?

Hi folks, thanks in advance for any insights you can offer.

I have an 05 Prius, ~335k miles. Ever since I've owned it, about 2 years, the steering has felt a little bit loose. Like, I'll be driving straight down the highway holding the wheel dead center, then (with no wind, but as if I'd been blown by a gust of wind) I'll be going a bit sideways and have to correct the steering. Then I'll have to correct the other way. That might sound like worn tie rod ends or rack & pinion, but I'm pretty sure it's not either of those things. Also, I have not noticed this problem associated with any uneven tire wear.

I started taking apart the dash to look for problems inside. I was able to hold the lower/intermediate steering shaft steady with vise grips while turning the steering wheel a bit back and forth, which seemed to narrow the problem down to higher in the steering shaft. I kept taking things apart, and removed the top of the bearing in the steering shaft. That ended up showing me this (see pic), which definitely seems to be the problem. It looks like the teeth here are supposed to fit together, but they're just sitting on top of each other. I do see play at this point, while clamping the shaft below the bearing and trying to twist the shaft above the bearing, but it's not enough play to fit the teeth on the upper part into the slots on the lower part. Can anyone help me here...what is this supposed to look like, and either a) how do I get it there, or b) do I need a whole new bearing or something? I tried to torque the upper shaft while bracing the lower shaft, or even bracing the tires outside the car, but that didn't quite get me there. Part of the reason I came here instead of trying more torqueing is that it doesn't even look like the slots on the lower thingy are big enough to fit the teeth on the upper thingy, but maybe they are. Also, why are there 2 upper thingys stacked together?

 

Awesome! Thanks for that. So does that mean that there is supposed to be a little bit of room for play between Detection Ring 2 and Detection Ring 3 in order for them to function? Because there is visible play between those rings without even trying all that hard while twisting the upper shaft, with the lower shaft left free (the only resistance being from the tires, which are on the ground). Put another way, the play that I can feel & see between Ring 2 and Ring 3 with everything disassembled looks very similar to the play I feel while driving down the highway.

 

Thanks for your help above, ChapmanF. It doesn't look/sound/feel to me like the input or output shafts are slipping relative to the torsion bar. I do wonder, though, if it's possible that the torsion bar itself has lost some springiness...as you say, a lot can happen in 335k miles. It feels like the upper shaft can wiggle sideways/rotationally more than it's supposed to before the lower shaft responds at all. Anyway, I'll put it all back together and pay more attention to how it feels while driving.

The thing that I find odd about this is that it doesn't seem to have gotten worse or changed at all in the two years I've had this vehicle. I was mainly curious and had some free time the last few days, and was able to rule out a couple possibilities like worn steering elbows. Realistically, if I don't have a flash of insight about this, I'll probably be continuing to drive it with this old-age quirk until the vehicle disintegrates.