As the others said, check ball joints and bushings...although it is also possible to have a worn steering gearbox, or a worn steering shaft (that connects the wheel to the box).
As to the brake calipers...as the other said, make sure you do a comprehensive flush of the brake hydraulic system! This is an often-neglected maintenance item, but really, it should be done annually. New brake fluid is almost clear.
As to how to replace the calipers...on '80-'86 trucks, there's a metal key at the bottom of the caliper with a flat spring between the key and the caliper itself. There's a bolt holding the key in place; remove the bolt and take a flat punch and hammer the key out. Once the key's out, rotate the bottom of the caliper out and the top should pull out.
Take a look at the pictures:
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When you reassemble it all, make sure to liberally apply lubricant to all sliding surfaces, most notably where the top and bottom of the caliper slide on the mounts. I had a caliper seize on a sliding surface...the piston was fine, but the caliper ended up not being able to move when the piston retracted...the other three pads had over 50% material left, but one pad was worn to the metal
Hope this helps some...good luck