Yeah this is not normal.
Three possibilities most likely:
1.
Your steering gear box has too much slack in it.
2.
Your steering column rag joint has given up the ghost.
3.
Your steering linkage is not matched with your lift (subject matter in the link AlwaysFloored posted).
If #1 turns out to be the case, there is a meshload adjuster on the top of the steering box that might help to take up the slack, but if the box is very worn, this won't remove the slack entirely (in which case you'll need to replace it).
WARNING: Do not overtighten the adjuster, otherwise you'll bind up the box which (at best) can damage the box, or (at worst) cause you to lose control of the truck and lead to a collision.
Best way to make sure the box doesn't bind is to disconnect the steering linkage from the pitman arm... Loosen the jam nut and then tighten the inner screw just enough until you feel it bind slightly right as you rotate the steering across center, then back it off just enough to relieve the bind, and retighten the jam nut.
There should be some past threads on this subject if you put in the term "Meshload" into the forum's Search box.