I finally sprung for new rear leaf spings for my 95 Cherokee Sport. Also replaced the rear shocks. What a huge difference! I no longer get that squeeky thud when I come to a stop, and that mysterious driveline vibration that I had for over a year is finally gone.
This was an expensive repair but worth it to me. People tell me I'm crazy for putting a lot of money into the Jeep because it's a rust bucket, but the bottom line is that I like driving the Jeep.
Also, there is no way in hell that I could change the springs or rear shocks myself. I don't have the tools or the skills.