im pretty sure the subframe from an 04+ will fit, I had a 97 and was going to do the swap, I do engine work for a GM dealer and bought a core out of a 06 impala ss, but I sold my 97 and bought a 04 gtp and dont want to change out the 3800(love my supercharger)! anyways, I think you can get a harness made from Painless, but im not sure, I was just going to make one, anywho if anyone needs a ls4 i have one