The upper ball joints last longer than the lowers. For the lowers, it's useful to get the ball joint remover kit from harbor freight.
The Moog "Problem Solver" ball joints are slightly over-sized for the situation where the lower ball joints have been replaced a few times and the hole in the lower a frame is worn out.
Complete front suspension kits are on ebay with upper control arms with ball joints, lower balljoints and tie rod ends for about $100.
Some outfits sell a new upper control arm that accepts their own replaceable ball joint.
Most sell the complete upper with a non-replaceable ball joint, which is like the original.
Given that the uppers hardly wear, not sure it makes a big difference which way you go.
It's an all day Saturday job. Since you'll be "going in there" you might want to consider replacing other things. New Rotors needed?, New wheel bearings? New tie rod ends?
The parts are inexpensive compared to the value of your Saturday. So you don't want to waste another Saturday going in there again for something you missed.
The Arabs have an old saying..."Trust in Allah, but tie up your camel".
Gen 1 Sport Trac owners have a similar saying... "Trust in Ford but, check your body mounts."