Put the jack under the outer most end of the lower control arm. Rise it up as much as you can without lifting the frame off the stand.
Remove the nut on the upper ball joint, then screw it back on a couple of turns.
Remove the nut on the tie rod end, then screw it back on a couple of turns.
Now turn the steering knuckle so the the tie rod end is swung out.
Take a BIG hammer and wack the end of the steering arm where the tie rod end connects. The tie rod end should jump out after a hit or two. Remove the nut and move the tie rod out of the way.
Now do the same thing to the steering knuckle where the upper ball joint connects. This time it will jump apart! The jack is in place and will hold the lower control arm and steering knuckle so it won't fly apart.
Slowly lower the jack and the spring will fall out.
The reverse of this "may" not work if reinstalling the stock spring as a lot of pressure is needed and the truck may lift off the stands, but using a softer/shorter spring the arm will lift easily so you can reconnect the upper ball joint.
Having the nuts on a few threads will reduce the chance of damaging the threads if you miss with the hammer.