Is that noise a strut, bushing, shock or what???

With 97K miles logged, it is quite likely that your struts/shocks need to be replaced.

It is also possible that a front sway bar bushing is worn, allowing the sway bar to thump against the body as you go over a bump.

 

And here is my thread I started today explaining how to buy 4 new stuts, mounts & bellows (dust sleeves) for under $300 + tax:
http://priuschat.com/forums/gen-ii-...1-4-struts-mount-bellows-less-than-300-a.html

 

I've got an 05 with a few less miles on it but I think the rear right suspension was worn out two years ago (slight vibration from right rear at highway speeds that didn't go away when buying new tires or rotating tires).

What is on the rear:

Shocks
springs
Struts

All 3, some combination of 2?

Only one of them but all 3 names are used to describe the one set of things that gets replaced?

 

Each side of the rear suspension has a shock surrounded by a coil spring. The coil spring is typically reused unless your car has logged so many miles that the car is sagging - in that case the coil springs would be replaced.

The difference between a strut and a shock is that the former can support a sideways load not along the axis of the strut's compression. Therefore the strut is substantially more robust in its construction.

 

No sag that I notice and I'm not looking to lower the car so I'll keep the springs.

So I should just be looking at shocks, not struts?

 

If you wish to replace the rear shock-absorbing parts only, then you would just purchase and replace the two rear shocks. Optionally you could replace the rubber insulator rings that fit between the shocks and the bottom of the coil springs.

If you also wish to replace the front shock-absorbing parts, then you would need to purchase and replace the front struts as well as the pleated rubber covers that keep dirt out, the top strut bearings, and the rubber insulator rings between the struts and coil spring bottoms.