Here's someones post kinda easier to understand.
You need to plot your suspension on a garage floor.#Get yourself some fishing line and a washer. You can use a plumb bob if you have one.#Lift the car up on 4 jackstands as high as you can go. Make sure the stands are under the suspension.Pick identical points along the car front to back and use your marker to write down on the ground where the point is. I started with the frame rails and marked them at 3 points and then used a square to trace out a line on the floor.#Then move to your suspension componants and trace/measure everything. It won't be long before you get to see the big picture of how everything is aligned. I used the center of the LCA mounts for reference points in the rear, along with the axle centers and compared all the measurements.You can measure from a front point across to a rear in an X pattern if you want to see if the car was twisted up. Mine was less than a 1/4". I imagine that's well within Ford factory spec anyways.#It sounds ridiculous, but it works quite well and is pretty easy if you can use a marker, and a tapemeasure.#I did it to square up the rear end in the car after I added a full UPR kit and before I took it for a 4 wheel alignment. Seems to have worked well, as I had zero problems hooking and the car tracked true and was incredibly predictable, even at 143mph.__________________Ian