The GM 700r4 is a 4-speed automatic transmission with overdrive. It was introduced in the early 1980’s, as way to make their V8 powered cars and trucks more efficient. In a world filled with rising gas prices, the General needed to keep its product line relevant.
Adding a 4th overdrive gear allowed them to make their sports cars and pickup trucks more affordable to drive. The 700r4 transmission replaced the 3-speed TH350, and became a popular upgrade for older rear wheel drive GM vehicles.