I don't know about a 63 but the with the AD trucks, you can only install the Pitman arm one way. If the Pitman arm is the wrong one, it will cause this. Also, the steering box can be put together with the gears one tooth out and this will cause this.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!