This product page is for tuning GM T43 Transmission Control Modules (TCM) for use with the 6-speed 6L80E/6L90E electronic automatic transmissions. This service is required when using a transmission that was not mated to your engine when the engine computer was programmed. Failure to have the TCM configured at the same time as your ECM will result in inoperable conditions. It is NOT performance-based tuning although the engine and transmission can be expected to operate at higher levels due to changes in the heavy safety removed from the OEM tuning. 
 
The T43 TCM is located INSIDE of the 6Lx0E transmission where the connector body mates and must be carefully removed and shipped to ensure damage does not occur.