MAILORDERTUNER.COM: ECM / TCM For Gen 3 and Gen 4 LSx an LTx

Only The Gen 3 ECM has a built-in TCM. Anytime changes are made for stall, tire size, and shift points: will need a TCM. 2007+ T42 TCM can be found behind the PCM 6l80/6l90, the TCM is found inside of the transmission. You will have to remove the valve body to access the TCM so it can be sent in.