Sonnax 200-4R Valve Body Repair Kit

Upgrade your 200-4R transmission shift quality with this Sonnax valve body repair kit. The 200-4R is critical in the Buick Grand National and GNX platform where it must handle turbocharged torque loads. This kit modifies the valve body hydraulics for firmer, more consistent shifts while reducing slippage and extending clutch life.

Complete with detailed instructions. Compatible with all 200-4R transmissions from 1981 to 1990 in Buick Grand National, Regal, GNX, Corvette, Monte Carlo SS, and other GM vehicles. A must-have upgrade for any 200-4R rebuild, especially in performance and turbocharged applications.