The Stovebolt Site Forums The Shop Area Driveline Threaded shackle wear

If your bushings haven't worn thru to the springs themselves, count yourself lucky. Mine were worn enough that I needed to replace springs as well. It sounds like yours are in relatively good shape, and had possibly been greased like they should have been. My truck started it's life as a fleet truck and probably got rode hard and put away wet.
If you don't want to replace the bushings, you could remove some of that wear by just installing new pins. But to do the job correctly, I would replace both the bushings. Not a hard job. I used a ball joint press which worked well. I didn't even worry about threading the pins out. I'm not sure a couple of them could even have been removed.