Upper ball-joint axial play...
Upper ball-joint axial play is checked by taking all the weight off the tire. Axial play is ball-joint endplay.
Camber is especially crucial...
Camber is especially crucial for handling because it determines how much contact patch we have. Contact patch, all of the tread on the pavement, is what enables us to cut apexes without winding up in the weeds.
For '79-up, caster adjustment happens via MacPherson strut movement around the top caster/camber plate, making alignment a cinch for late-model fans.
What Is Toe?
Although most of us think of toe as those piggies on the ends of our feet, toe takes on a different meaning with cars. Toe is the last adjustment checked during front-end alignment. As its name implies, toe-in is the angle of the front wheels as they relate to a car's longitudinal axis.
Toe is adjusted at each of the tie-rod end assemblies in the steering linkage. When adjusting toe-in, you are adjusting each front tire's attitude as they relate to each other. Proper toe adjustment begins with the steering wheel at dead center, exactly in the center of lock-to-lock travel. If your steering gear is three turns from lock-to-lock, steer all the way left, then clockwise back 1-1/2 turns to center. Once the wheel is centered, lock it in the centered position during toe-in adjustment.
When measuring toe-in, first determine the distance between the right and left tire sidewalls (or rims) with the wheels straight ahead. Measure front and rear distances, and do the math. Toe is always set as toe-in, with both front wheels pointed a pinch inboard to allow your Mustang to stay on course and make light work of steering wheel return-to-center. When steering wheel return-to-center is sluggish, it's usually a toe-out problem.