The leverage the shock has on the axle has probably changed. I bet the body mounts are the same, I don't know for sure. I'd order new shocks for the later model axle and ask for aggressive rebound dampening and softer compression dampening to smooth out the ride. If the mounts are radically different you can get a universal bushing and probably make your own upper adapter.

91 YJ
2 Seater Sand Rail
Handfull of other fun toys...
And a brand new, spit shined, B.S.
Oh, and a job to boot.