B&M® Shift Improver Kit™ for 1981-1990 Chevrolet, Buick, Olds, Pontiac and GMC TH-200-4R transmissions, recalibrates your automatic transmission for optimum performance and extended life! Select the mode that best suits your application Provides crisp shifts on any stock automatic transmission Eliminates shift overlap and excess wear on clutches and bands due to slippage The B&M Shift Improver Kit the easiest way to get the stout performance you've always wanted out of your automatic transmission - and you get two modes of performance to select from: Heavy Duty, or Street/Strip. It's our least expensive and simplest to install kit. All you need are some hand tools! 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! STAGE 1. HEAVY DUTY Firm positive shifts without loss of driver comfort for improved performance in all street vehicles. Recommended for regular passenger vehicles. STAGE 2. STREET/STRIP Provides positive shifts for high performance street use or for competitive events. This level is for the enthusiast who wants the hardest, quickest possible.