ok after talking to alan from nelson performance about an 07 envoy denali having a TAC module, hes not 100% sure if it has one or not, so if anyone knows if it has TAC let me know thanks. If it does do you know the part #. I have talked to many about this but some say it does and others say it does not. i dont know if this helps or not but its a GEN4 motor and the ECM and the TCM are seperate.