I have a 99 jeep grand, and i can't get rid of the clunk in the rear end! So far i've replaced the shocks, upper ball joint, sway bar links, the bushings in the upper wish bone suspension, and now I'M STUCK, HELP!!!!!!!!!!!!!!!! It always sounds like something is loose! Could it be my budget boost 2" lift? I have rough country Shocks for a 2-3" lift too!!!!!!  

When does it clunk? Going straight, turning, accelerating, coast, braking, shift in gear etc.  

If your coming to a stop and your fully stopped, do you feel the clunk? and sometimes when you take off from a stop do you feel sorta the same? if so your rr pinion yoke may need to be replaced. My 86 sub would do that stopping or taking off from a stop and I had a lot of slop and a new yoke fixxed my problem.  

It's when i hit bumps in the road. It's like a bad bushing or loose bolt? Maybe the coil spring and the 2" budget boost spacer? It's driving me Crazy!  

well then I'd take a big ass rubber mallet and start checking mounting areas,bushing, brackets, link arms by smacking them to see what is loose...if nothing then jack it up to relieve the weight off the suspension and smack some more. NOW not too hard on the smacking!
I had to do that one time, seemed to take forever to find the noise, but smacking it found I had a loose bolt on the spring hanger and the bushing were shot, the rubber was completly wasted.  

Spare tire/jack hold downs loose?  

I'll check it out! THANKS alot for the help! I'll keep ya posted on what i find out! Hope it's just a loose bolt!  

Still making a banging noise, can't find anything loose or wore out! I'm Stuck  

Did this start after you put the spacers in?
Have you checked your pinion angle. I've seen 2 inches cause a little wabble in the drive shaft and in turn cause rattling some where else. If thats the case skidplate spacers will do the trick.  

You said its when you hit a bump... are your shocks bottoming out?  

So the muffler bangs against the frame in the rear because the rubber bushing is too loose!