you might want to check clifford performance for stuff like that.
Do you need to replace them for any reason, or are you just after performance? If its the performance thing, I've heard that you don't get big gains from doing that. You'd get better gains from mods like weber or holley carb upgrade or Mopar MPI, Headers/Intake manifold, 4.0l head swap, and even cams if you want to take it that far.
