Interesting, could be the control arm bushings but the factory ones being rubber and all I would not have guessed first. But if they are failing, maybe. I've driven mine through water and they get sprayed with mag chloride all winter and they are hanging in there. Like I say, only that frozen bolt so far. If spraying them directly with lube makes them quiet down, that sort of points at them, doesn't it?
As far as being super quiet, yeah I'm not the guy. I drive an old truck and I wish I could isolate a noise down to a single part. But I have noticed that my poly leaf spring bushings start to get squeaky after about 6 months. I also get a high pitched squeal/squeak from the bracket that holds the leaves aligned. The one riveted to the overload in the back. I wipe a finger's worth of grease along the inside of that and things get much quieter for a while. Body mounts, door hinges, body panels. It all makes noise on mine after 17 years (8 of which I know have been fairly hard wheeling with a Wildernest).