Be careful adjusting that screw as you can bind up the bearings in the gear box... I posted this in another thread (linked below). Be very carefull about tightening the nut too tight, you want some play in the wheel, that nut is for taking the slack out of a brand new gear box.
http://www.powerstroke.org/forum/6-0-drivetrain-problems/210211-06-f250-slack-st-wheel.html
Here you go!
Start the truck.
Turn the wheels from left stop to right stop completely then back to the left approximately 45 degrees.
Shut the truck off.
Hold the meshload screw, loosen the lock nuts then adjust the meshload screw no more than ¼ turn at a time (Rotate clockwise to increase, counterclockwise to decrease)
Tighten locknut to 30Nm (23 lb-ft)
Start truck and turn from left stop to right stop completely then position the wheel at center. Test for play. If too much then repeat steps. DO NOT tighten the meshload screw to where there is no play in the steering wheel at all. This can cause you bearings to bind. You want some play in the steering wheel.
Since you’re doing this you could do a power steering flush as well.
Remove the reservoir cap.
Suction the fluid out of the reservoir (a turkey baster is what I’ve always used)
Disconnect the return hose. Plug the inlet port.
Attach an extension hose to the return hose and place in a bucket.
Fill the reservoir with new fluid.
Start the truck and turn the steering wheel all the way to the left then turn the truck off.
Refill the reservoir.
Start the truck and turn the steering wheel all the way to the right. Turn truck off.
Repeat filling the reservoir and turning from right to left until the fluid coming out of the line is clean as new.
Once done just reinstall the hose and fill the reservoir to the proper level.
DO NOT UNDER ANY CIRCUMSTANCES LET THE POWER STEERING RESERVOIR GO EMPTY!!! This can cause air in your pump and lines and lead to problems like poor steering, pump overheating and loss of power steering.
I don’t think I missed any steps anywhere, been a while since I’ve done it. I got the torque specs for the hold down nut after calling my dealership to ask what spec was.