The 4T80E is a series of automatic transmissions from General Motors. Designed for transverse engine configurations, the series includes 4 forward gears. The 4Txx family is an evolution of the original Turbo-Hydramatic 125 transverse automatic introduced in the 1980 model year "X" body. The 4T80-E transmission is electronically controlled and features an automatic overdrive transaxle with an electronically controlled torque converter clutch. The 4T80 originally used a viscous clutch, but this was changed in 2005. The 4T80 is built at Willow Run Transmission in Ypsilanti, Michigan.