A common problem in GM 200-4R and 4L60 transmissions is burned bands and/or 3-4 clutches. This failure can be reduced by eliminating throttle boost oil leaka
200-4R Boost Valve & Sleeve - Cobra Transmission
Sonnax 77917-04K TV Boost Valve Kit .500 Dia., Factory-Style Sleeve (No O-Ring)
Sonnax Oversized Primary Pressure Regulator & Reverse Boost Valve Kit - 47740-02K
Whatever It Takes Transmission Parts
Sonnax Boost Valve Kit - 89010-02K
Sonnax Oversized Pressure Regulator Valve - 77917-07
Sonnax Reverse Boost Valve Kit - K77898
Sonnax Authorized Distributer Phoenix Transmission Parts, Inc.
Sonnax Boost Valve Kit - 96201-08K