Guys:

I have pretty much refreshed the front end of my truck.

new LBJ, new inner and outer tie rods, new rack bushings, new rack guide, new shocks, alignment, column tack weld mod.

The truck drives very well, and I do have a shake at 65 mph but its cause the shop that mounted my duratracs is staffed by tards. My other set of wheels rolls great.

What my truck is doing, is if I am on a stretch of highway the wheel will sort of quickly turn one way and return to center. Its subtle, and its more something you feel in your hand. It doesn't dart all over. Similar to how when you go over a speedbump sideways the wheel will move as first one then the other tires roll over it. (the wheel moves less than an inch, just to clarify. Its not like some sort of violent movement.)

Is this just a function of suspension geometry? Or is there something I am forgetting to check?

Looks like you have most everything covered, I would suggest checking the control arm bushings. If they are worn or broken it will change the geometry and make the car shift. Lower bushings usually go before the uppers.

You rack guide bushing may be too loose, you could try snugging it up a bit and see if that helps.

Or the rack itself could be worn and in need of replacement.

Fyi:

I swapped from the duratracs to the stock 265-70 A/Ts that it came with for a long trip I had planned, the vibration is gone and the wheel movent is nearly imperceptible. So, it seems the added unsprung weight and vibration of the tires is 90% of the problem. I'll probably just live with it, as I'm not sure it's even a problem just a fact of driving a tall truck.

I would second checking the LCA bushing. My 99 would tend to pick its own line on roads that were not level or had any type of grooves. Literally would have to fight it to stay straight in many situations. Pretty easy to test with the weight off the arms. I could see a fair bit of play just sitting under the vehicle while someone turned lock to lock.

Definitely LCA bushings. May as well do UCA bushings while you're in there. And maybe rear bushings ;)