This B&M® Shift Improver™ kit fits all 1971-1977 Chrysler, Dodge, and Plymouth Torqueflite A727 transmissions, along with A904 transmissions that originally came behind V-8 engines. This kit recalibrates your automatic transmission for optimum performance and extended life by eliminating shift overlap and excess wear on clutches & bands due to slippage. You get two modes of performance to select from Stage 1 Heavy Duty, or Stage 2 Street/Strip. Stage 1 gives firm positive shifts without loss of driver comfort for improved shifting performance in all street vehicles. Street/Strip is for high-performance street use or for competitive events for the enthusiast who wants the hardest-hitting, quickest possible shifts. All you need are basic tools, and the included installation instructions, and in the space of an afternoon you can turn your transmission into a B&M-tuned unit! Ask the thousands of satisfied customers that have installed one in their transmissions!