For the 98+ SE/LS V6 MTX's and SVT's the front springs are the same. Rear springs on the Ls V6 MTX and SVT are the same, rear springs on the SE V6 MTX and ATX are the same.
The mailing list archives are down right now, but check tomrrow or the next day, and look at
this message . It explains what I just summarized above, showing codes and such for the springs.