In GM TH350 and TH350C units, the intermediate servo bore becomes scored from repeated cycling. The spring side of the piston has line pressure present in R, N, D. Excess leakage at the servo piston results in low line pressure and delayed engagements. During forward speeds, oil loss affects shift quality and reduces clutch life. To salvage cases, install Sonnax intermediate servo sleeve kit 35709-01K.

• Contains an aluminum sleeve and a replacement piston with a PTFE seal
• Drop-in solution requires no machining of the transmission case