Ok first thing first you want to do is remove the box and place it on a work bench, or the tail gate of the truck.

then you need to go down to your local auto part store that rents out tools. This cost my 90 dollars but i got all of it back when i returned the tool... so basically i did it for free.

take the nut and lock washer off the end of the shaft that holds the pitman arm on. and place the Pitman arm puller over the pitman arm. You want a snug fit but not tight agasint the shaft. You just dont want the tool to slip off the arm.

you may want to note how far the pitman arm goes onto the shaft so you can return it to its proper place.
You then want to tighten the screw bolt down( it helps to sometimes oil the threads lightly on the puller to pull the arm off if it gets really hard to turn lightly and i mean lightly tap squarly on the head of the top of the bolt and try turing it again it should get easy to turn. It shouldn't take to much work to remove the arm.

Then to put the arm back on the new box it should be as simple as linging up the splines. Most steering boxes ive seen will be made so you can only put them on one direction. Place the arm in its proper spot and put the lock washer and nut back on and use a wrench to seat the arm back to its proper alignment. Then torq the nuts to its proper torq and your done and can place the steering box back on your truck, and return your tools if you rented them.

thank you for reading and if i missed something let me know.