GM

3T40 (125C) Transmission

Tech Resources View all Transmissions
Remanufactured Valve Body

Required

3T40 (125C) Remanufactured Valve Body GM003

3T40 (125C)
Remanufactured Valve Body GM003

With 3-Prong 2nd Switch

Required

3T40 (125C) Remanufactured Valve Body GM004

3T40 (125C)
Remanufactured Valve Body GM004

without 3-Prong 2nd Switch

Sonnax rebuilt valve body GM004 is no longer in production. Please check with your distributor for availability. For service inquiries, please see details on Sonnax’s Limited Lifetime Warranty on remanufactured valve bodies.

Internal
Zip Kits

Bearing Kit SBK-G13

1985 & later

Zip Kits

Differential Carrier-to-Case Shim 75410-10

  • Material: Steel
  • Thickness: 0.010"
  • Inner Dia.: 1.445"
  • Outer Dia.: 2.170"
    Helps cure:
  • Driveline noise
  • Excess backlash
  • Reduced differential bearing life
Zip Kits

Driven Sprocket to Case Thrust Bearing 35400C

  • Bearing Style: Enclosed
  • Inner Dia.: 2.134"
  • Outer Dia.: 2.890"
  • Width: 0.140"
Pump
Zip Kits

Pump Shaft with Bearing 75877A

1984 & later

Zip Kits

Pump Vane 1280

    Helps cure:
  • Lost or damaged component
Case
Zip Kits

Accumulator Piston Kit 75921-01K

    Helps cure:
  • Burnt Forward clutch
  • Poor shift quality
  • Wrong gear starts
  • Delayed engagement