I have a problem with my steering shaking at highway speeds. It is not all the time though. I can be driving for a while and no shaking then it starts for a bit. Go around some corners/drive for a while then it goes away for a bit. I am confused as to what this is because I have just replaced pitman arm, idler arm, and tie rods (it was shaking worse before replacing these). It has been aligned as well after all of that.
I can't seem to figure this out. Checked the ball joints and they seem ok also the wheel berings seem ok too but I am not 100% sure how to check these properly.
Any help will be great because this is a little annoying. Oh ya I also have about 30% wear left on my 285's and everything is stock in the front end (ie no lift/leveling kit, etc.)
Thanks

To check wheel bearings: jack up wheel clear of ground, push & pull firmly in & out at the top of wheel, there should be no appreciable play.
Check your steering damper (is it still efective?)

my brother had the same problem. it turned out to be a warped front rotor.

I had the same problem, and the other day when i jacked up the front end and was greasing it i noticed play in the drivers side wheel bearing. I took off the dust cap and i was able to unscrew the huge nut by hand. Tightened it up with an impact gun and the shake went away. Steering is 100% better.

How would one check the steering dampener?
I am not sure how much resistance there should be on it.
I know what mine felt like when I had a lifted truck with a Rancho one installed but I don't know what the stock one should be like.

Just disconnect one end & see what it feels like, also how much free play it might have when changing direction.

Once on a small cab over Toyota truck we converted from man to power steer, also had wider wheels/ tyres than stock, then gave it more + caster (for road feel) would then sometimes start violently shaking arfter hitting a small bump in the road, we fitted a steering damper which the fixed the problem.