GM 200-4R High Performance Transmission Superior Shift Correction Kit This Shift Correction Kit from Superior will improve all GM 200-R4 High Performance Transmissions from 1981-1990. This Shift Correction Kit is for High Performance applications only. This Shift Correction Kit helps eliminate the following problems: Super positive shifts, prevents clutch & band failure, improves overall performance, includes .471 boost valve, superior for performance cars and trucks. This Shift Correction Kit will come with installation directions in English and illustrations. We also offer a regular version of this Superior Shift Correction Kit for non High Performance applications.