• No engine braking in manual 2nd
  • Low line pressure in Reverse
  • Low line pressure in Neutral
  • Low line pressure in Drive
  • Delayed engagement


Case bore wear and oil loss at the intermediate servo.


Sonnax intermediate servo sleeve kit salvages the case, and eliminates the complaints caused by oil loss.

350, 350C

Intermediate Servo Sleeve Kit
Part No. 35709-01K

View Instructions Find a Distributor

In GM 350 and 350C 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
  • Sleeve
  • Servo Piston
  • Seal PTFE
  • 35709 01k combo
  • 35709 01k