Pitman Arm teeth wear

Start by swapping the Pitman Arm, that’s usually the culprit. Steering box splines rarely wear unless mileage is insane.

 

Maybe some information for you here to get you looking in the right place.

https://youtube.com/shorts/Vl0586Wue3g?si=UBi5Q4BahYc3qySd

 

Before you start replacing anything, I would get someone to help you by getting in the truck and rocking the steering wheel side to side quickly like they do during inspections and you can be looking at the ball joints, pitman arm and steering column to see what’s loose. Just my opinion.

 

Just grab the steering shaft and twist it back and forth you'll be able to see pitman arm play on the shaft it's obvious.

 

More likely the pittman arm than the shaft. I've never seen splines on the shaft damaged unless a well worn arm was left too long.

But if you're having tire wear issues, it's probably not coming from there, though it can definitely cause driveability issues.

As @rollin coal said, you can see it move pretty easily.

 

Splines on pitman arm or steering gear will not wear regardless of mileage unless the arm has been run loose.