This kit allows fully automatic operation of the torque converter clutch in 4th gear when retro-fitting a vehicle with a 2004R transmission, or in 1981-1990 2004R equipt GM vehicles that no longer use the factory ECM to control torque converter clutch strategy. This kit easily installs with the transmission in the vehicle. A simple one wire hook-up to the transmission is all that is required after installing the supplied oil resistant wiring harness with integral heavy duty lock-up solenoid, OEM pressure switch, and single wire case connector. Includes complete and concise installation instructions. Remember the other big name kits DO NOT include a replacement solenoid.