I realize this is a long-dead thread, but Google seems fond of it, so I wanted to get a solid answer here.
I just did all four springs on my 95 YJ, though I got all new springs and bushings.
The thing that I didn't know (and I wish I knew!) was that the springs have two different kinds of bushings -- a larger one called the main eye, which mates directly to the frame, and a smaller one called the shackle bushing, which mates (you guessed it) to the shackle, which then mates to the frame.
The Main Eye bushings are one piece - an outer steel tube, lined with a thick rubber or poly bushing, which is lined with an inner steel sleeve. This whole assembly is very solid, and fits in to the main eye on the spring very VERY snugly.
I got new, OEM-spec springs, and it took a tremendous amount of force (and a big-ass bench vise) to get them seated.
The Shackle Eye bushings that I used are a three-piece assembly. There's two Poly bushings that fit in to the eye (one on each side) and a steel tube that slides in the center, holding them in place during mounting.
For each spring, you'll need a main eye bushing and a shackle eye bushing.
Good luck, and may the tires ever be below the rollbar.