Here's my recent experience: I wanted a 1.5 inch lift shackle set for my Rodeo, and I also had bad squeaking from the stock bushings.
Taking it all apart, the stock shackles were pretty hard to get out, because they were so badly corroded that the shafts on the shackles were really misshapen and rough.
The front shackle on one of the leafs popped right out with the first hammer strike. No wonder, the outer sleeve was cracked all the way through... source of the squeeking found.
The other leaf spring didn't want to come out at all, I tried driving a large flat tip screwdriver into the end of the leaf eye to spread it, and that didn't work at all... broke the screwdriver actually.
I then got out a power drill and drilled out as much of the rubber bushing as I could. The inner metal bushing came out, but I still had to get out my blow torch and burn out the rest. Once you light it you can start scraping it out as it melts, no need to burn it completely out. Remember to be safe and have a hose or fire extinguisher nearby.
Anyway, after I got it burned out enough, I was able to get my sawzall blade in there, and I made a cut through it where the leaf spring eye gap is. After I had it cut through, I used a chisel to bend one end of the cut bushing in on itself. I had to bend nearly half of the bushing in before I was able to pound it loose. I was completely fused to the leaf by corrosion...did I mention how much PB Blaster I had sprayed on it? No help.
The bushing I used are the ones sold by Independent 4x. I recommend the black bushings, not colored. They come with just enough grease to lube them up. When I put the bushings in at the back and went to put the new Calmini shackle on (I probably should have gotten the Independent 4X one, but no matter), I discovered that I couldn't slip the shackle over the bushings. I had to take the bushings out and chamfer them a little bit on one side with my dremel. I was then able to put them back in and use a BFH and pound the shackles on and the leaves into the shackle ends.
The front replacement bushings are split type, and go in really easy and fit perfectly.
Overall, I am very happy with the poly bushings and lift shackle. Even if you don't want to lift, I highly recommend replacing the stock shackle. Due to the corrosion pitting that I found on mine, I wouldn't have been able to re-use them if I had wanted to. The ride now seems smoother and tighter than it ever was, even when it was brand new in 95.
Here are the bushings I used:
Independent 4X bushings, buy the black ones!