if its the overdrive you have the 4l60 A.K.A 700 R4. 4l80e came in the early 90's. if i were you i would not install the b&m . i built these things by the truck load and i would rather install the trans -go jr kits. . these kits are designed to correct and update the valvebody and give a longer lasting life to your trans instead of a hard or neck snapping shift that b&m creates.