I lived on Ft. Leavenworth army base in the late 80's and our neighbor had one but his brother didn't know how to lean I guess I keep it on two wheels! The gear box I doubt..tires yeah depends or how long they've been that way..So the vibe is more from the s-wheel or your seat?

 

Feels like its the floor board...the tires I bought new&have less then Id say 1500 miles on em...I dont drive alot especially since the shaking has gotten worse.

 

May e I didn't read clearly, how long has the lift been installed in relation to the shake? How are your driveshaft angles? Too steep and your u-joints get over worked...
You mentioned bearings, did you do both sides? If one side is bad, the other is probably close behind.

 

Well I had a slight shake ever since Ive owned the truck but nothing too bad,only reason I remember is because. my buddy asked me was it suppose to shake like that&that's the first time I noticed it.That was 2 years ago.Then I put the body lift&leveling hit on around mid summer this year&it has progressively gotten worse@first I thought I had a miss but that has been ruled out its hard to describe but its like Im riding on a gravel highway is probably the best way to explain it.Its not super violent but its constant@low speeds its smooth..high speeds it gets pretty hairy.I didn't say anything about any hub bearing...Im actually trying to figure out how to check it&rotors.

 

lift the truck, check the tires by moving from 12 to 6 o clock position as well as 3 to 9..12-6 usually means bad hub assembly..there shouldn't be play..warped rotors will be felt when breaking

 

heresy from the alignment

 

In post 7 you mentioned changing a front wheel bearing. I'm not familiar with the 99, is it a whole hub assembly, or can you change the individual bearings and races? My 92 had bearings and races, two each per wheel. Gotta change all four bearings and races. It doesn't look like your alignment is too far out, but I'm not a pro. I'm still thinking a. Driveshaft issue. Maybe one is bent a little?

 

Post 7 in this thread or another?,theres another thread Im talking about buying a 1st gen that neees a hub bearing replaced..thats all Ive never even changed one before

 

I noticed my pitman arm coming off the steering gear box has some play where it meets the drag link should it or???I can take a video&Send it to ya

 

I should pay more attention to who is posting. It was roadram that posted about wheel bearings. Oops.
I would think that play in the tie rod between the pitman and drag link would put play in the steering wheel, and not result in a shake. Lifting your truck and checking for play in the wheels would be a good check. Put your hands on the sidewall of the tires, left and right, and try to wiggle the tire back and forth. Then do the same thing up and down. You shouldn't notice any play. Your rotors will only shake the truck when braking.