YOu have to take the truck in with the complaint of a "sustained shaking in the front end and steering wheel". Also tell them that you have already adjusted the air pressure in the front tires to maximum, all tires have been balanced, and front end alignment has been checked/set, and shocks have been checked and are ok. .
After letting them know that you have already done all these checks, drop the hint that the shop that worked on if for you stated that there might be a TSB that discusses this condition in particular...
Its not a recall, its merely a TSB, and yes, they can replace it under your extended warranty IF your truck is presenting with the conditions described in the TSB letter.
Basically, you are skipping the first steps that the dealership is going to do. Granted, you actually need to check this stuff first and ensure its not causing problems.
I got mine done at 23K due to the steering wheel feeling very uneasy and the truck would not settle into the road, adding the BD steering brace helped some, then it shook on me one day while hauling 1200lbs of feed. I immediately took it to the dealership and they could not duplicate the condition. I finally talked to the I. I. C. and explained that driving it across the parking lot wasnt gonna do it, and talked them into doing the TSB.