If you stare at the steering linkage from the front of the truck, you will notice the linkage is setup in a similar way to the TTB arms. If you look at any car or truck, say one with a a-arm suspension, you will notice the same thing; the steering linkage is configured to match the suspension, with the inner and outer tie rods setup to be close to the same length as the lower a-arms and at the same height.
They do this so when you are holding the steering wheel straight, going straight down the road, and the suspension moves up or down from a road bump, the steering linkage will "follow" the suspension. They will have close to the same arc of movement, so the steering linkage will not get longer or shorter in relation to the suspension.
If you mess with this relation between the linkage and the suspension, you will get what they call "bumpsteer". The truck will tend to dart one way or the other when you hit a deviation in the road surface, and you will end up fighting the truck to keep it in the road. The toe can be re-adjusted, but you will never get the severe bumpsteer out of it without a dropped pitman arm.
