1974 steering box question

[mntoy]

My 74 C20 truck has some slop in the steering, when driving straight down the road the steering wheel has to move side to side to keep the truck straight. This is just a little annoying and someone told me that this can be adjusted by loosening the nut on the steering gear and turning the allen stud in about a 1/2 turn then retighten the nut. This is the nut and allen stud you can see if you open the hood and look straight down on the steering gear. Is this correct and will this simple step adjust the slop in the steering gear? Any help would be greatly appriecated. Thank you,